The role of iron in host-microbiota crosstalk and its effects on systemic glucose metabolism

Exploring the gut microbiome’s influence on cancer-associated anemia: Mechanisms, clinical challenges, and innovative therapies

BACKGROUND

Anemia is a prevalent and challenging complication in patients with hematologic and solid malignancies, which stems from the direct effects of malignancy, treatment-induced toxicities, and systemic inflammation. It affects patients’ survival, functional status, and quality of life profoundly. Recent literature has highlighted the emerging role of the gut microbiome in the pathogenesis of cancer-associated anemia. The gut microbiota, through its intricate interplay with iron metabolism, inflammatory pathways, and immune modulation, may either exacerbate or ameliorate anemia depending on its composition, and functional integrity. Dysbiosis, characterized by disruption in the gut microbial ecosystem, is very common in cancer patients. This microbial imbalance is implicated in anemia causation through diminished iron absorption, persistent low-grade inflammation, and suppression of erythropoiesis.

AIM

To consolidate current evidence regarding the interplay between gut microbiome and anemia in the setting of malignancies. It aims to provide a detailed exploration of the mechanistic links between dysbiosis and anemia, identifies unique challenges associated with various cancer types, and evaluates the efficacy of microbiome-focused therapies. Through this integrative approach, the review seeks to establish a foundation for innovative clinical strategies aimed at mitigating anemia and improving patient outcomes in oncology.

METHODS

A literature search was performed using multiple databases, including Google Scholar, PubMed, Scopus, and Web of Science, using a combination of keywords and Boolean operators to refine results. Keywords included “cancer-associated anemia”, “gut microbiome”, “intestinal microbiota”, “iron metabolism”, “gut dysbiosis”, “short-chain fatty acids”, “hematopoiesis”, “probiotics”, “prebiotics”, and “fecal microbiota transplantation”. Articles published in English between 2000 and December 2024 were included, with a focus on contemporary and relevant findings.

RESULTS

Therapeutic strategies aimed at restoration of gut microbial homeostasis, such as probiotics, prebiotics, dietary interventions, and fecal microbiota transplantation (FMT), can inhibit anemia-causing pathways by enhancing microbial diversity, suppressing detrimental flora, reducing systemic inflammation and optimizing nutrient absorption.

CONCLUSION

Gut dysbiosis causes anemia and impairs response to chemotherapy in cancer patients. Microbiome-centered interventions, such as probiotics, prebiotics, dietary modifications, and FMT, have shown efficacy in restoring microbial balance, reducing inflammation, and enhancing nutrient bioavailability. Emerging approaches, including engineered probiotics and bacteriophage therapies, are promising precision-based, customizable solutions for various microbiome compositions and imbalances. Future research should focus on integrating microbiome-targeted strategies with established anemia therapies.

Crosstalk between ferroptosis and endoplasmic reticulum stress: A potential target for ovarian cancer therapy (Review)

Ferroptosis is a unique mode of cell death driven by iron‑dependent phospholipid peroxidation, and its mechanism primarily involves disturbances in iron metabolism, imbalances in the lipid antioxidant system and accumulation of lipid peroxides. Protein processing, modification and folding in the endoplasmic reticulum (ER) are closely related regulatory processes that determine cell function, fate and survival. The uncontrolled proliferative capacity of malignant cells generates an unfavorable microenvironment characterized by high metabolic demand, hypoxia, nutrient deprivation and acidosis, which promotes the accumulation of misfolded or unfolded proteins in the ER, leading to ER stress (ERS). Ferroptosis and ERS share common pathways in several diseases, and the two interact to affect cell survival and death. Additionally, cell death pathways are not linear signaling cascades, and different pathways of cell death may be interrelated at multiple levels. Ferroptosis and ERS in ovarian cancer (OC) have attracted increasing research interest; however, both are discussed separately regarding OC. The present review aims to summarize the associations and potential links between ferroptosis and ERS, aiming to provide research references for the development of therapeutic approaches for the management of OC.

Iron overload exacerbates metabolic dysfunction-associated steatohepatitis via the microbiota-gut-liver axis through lipopolysaccharide-mediated Akr1b8 activation

Iron homeostatic is closely linked to the development of metabolic dysfunction-associated steatohepatitis (MASH). However, the underlying mechanisms remain poorly understood. HFE knockout (KO) mice were used to generate mild iron-overload models. MASH was induced by feeding mice a methionine- and choline-deficient (MCD) diet for 4 weeks. Iron overload significantly exacerbated the pathologies of MCD-induced MASH, including liver injury, hepatic lipid accumulation, inflammation, and fibrosis. Additionally, iron overload reshaped the composition of gut microbiota, and fecal microbiota transplantation assay proved that gut microbiota from iron-overload mice contributed to hepatic lipid accumulation in control mice. Furthermore, iron overload-induced dysbacteriosis altered the metabolite profiles, reducing short-chain fatty acid levels and increasing lipopolysaccharide (LPS) levels. Notably, elevated LPS levels upregulated the expression of aldo-keto reductase family 1 member B8 (Akr1b8), which accelerated lipid accumulation and inflammation in hepatocytes. Above results indicated that iron overload promoted MASH progression through the microbiota-gut-liver axis, mediated by LPS-induced activation of Akr1b8. These findings highlight the critical role of iron homeostasis and gut microbiota in MASH pathogenesis.

Multi-omics driven biomarker discovery and pathological insights into Pseudomonas aeruginosa pneumonia

BACKGROUND

Pseudomonas aeruginosa (P. aeruginosa) is a leading cause of hospital-acquired pneumonia, contributing significantly to morbidity and mortality, especially in immunocompromised patients. Understanding the molecular mechanisms underlying this infection is crucial for developing targeted therapeutic strategies. This study aims to elucidate the local and systemic pathways and biomarkers involved in the pathogenesis of P. aeruginosa pneumonia through an integrated multi-omics approach.

METHODS

We performed a comprehensive proteomic and metabolomic analysis on clinical samples from patients diagnosed with P. aeruginosa pneumonia, including both bronchoalveolar lavage fluid (BALF) and serum to capture local and systemic host responses. Data were analyzed using advanced statistical techniques to identify differentially expressed proteins and metabolites. Pathway enrichment analysis was performed to highlight significant biological processes associated with the infection.

RESULTS

Our findings revealed a significant upregulation of biomarkers associated with neutrophil extracellular traps (NETs) and oxidative stress, underscoring their pivotal roles in immune response and inflammatory pathology. Key proteins such as LCN2, CALR, and TPI1 were identified as central players in NET formation and oxidative stress pathways. Our integrated approach uniquely highlights the simultaneous local and systemic impact of NETs and oxidative stress. Additionally, by analyzing both BALF and serum, we observed distinct disruptions in metabolic pathways, particularly those related to amino acid metabolism and energy production, suggesting a bioenergetic crisis in response to infection. The combined analysis revealed key interactions between local and systemic immune responses, indicating a reprogramming of host energy pathways to meet the heightened immune demands, contributing to disease progression.

CONCLUSION

This study provides a comprehensive understanding of the molecular mechanisms driving P. aeruginosa pneumonia by uniquely integrating BALF and serum analyses to explore both local and systemic host responses. Our findings highlight the dual role of NETs in both pathogen containment and tissue damage, as well as the metabolic reprogramming required to sustain immune activity. The identification of key biomarkers and disrupted pathways presents promising targets for therapeutic intervention, with the potential to refine diagnostic precision and improve patient outcomes.

CLINICAL TRIAL NUMBER

Not applicable.

Iron at the crossroads of host-microbiome interactions in health and disease

Iron is an essential dietary micronutrient for both humans and microorganisms. Disruption of iron homeostasis is closely linked, as both a cause and an effect, to the development and progression of gut microbiota dysbiosis and multiple diseases. Iron absorption in humans is impacted by diverse environmental factors, including diet, medication and microbiota-derived molecules. Accordingly, treatment outcomes for iron-associated diseases may depend on an individual patient's microbiome. Here we describe various iron acquisition strategies used by the host, commensal microorganisms and pathogens to benefit or outcompete each other in the complex gut environment. We further explore recently discovered microbial species and metabolites modulating host iron absorption, which represent potential effectors of disease and therapeutic targets. Finally, we discuss the need for mechanistic studies on iron-host-microbiome interactions that can affect disease and treatment outcomes, with the ultimate aim of supporting the development of microbiome-based personalized medicine.

Iron Modulates the Growth and Activity of Nitrate-Dependent Methanotrophic Bacteria by Reprogramming Carbon Metabolism

Iron is indispensable for literally all microorganisms, yet becomes toxic at elevated levels. Protein-based iron storage compartments, such as ferritins, play a key role in maintaining iron homeostasis when the iron level surpasses microbial requirements. However, the energy-intensive nature of iron storage raises questions about how microbes balance this bioprocess between growth and metabolism. Here, using nitrate-dependent methanotrophic bacteria with the simplified metabolic system as a model, we propose a novel metabolic reprogramming pathway regulated by iron storage that controls the balance between growth and activity. Isotopic labeling and meta-omics analyses revealed a striking contrast between bacterial abundance and methane-dependent denitrification activity in "Ca. M. sinica". Using microscopy and energy dispersive spectroscopy, we identified iron-rich nanoparticles within cells exposed to 40 μM Fe2+, alongside increased expression of genes involved in iron metabolism and methane oxidation coupled with denitrification. Additionally, we observed a shift from the energy-demanding Calvin cycle to the more energy-efficient serine pathway for carbon fixation, promoting the synthesis of glycine and succinyl-CoA, which serve as key precursors for iron storage proteins. These metabolic adjustments highlight a strategy for coordinating both substance and energy metabolism in nitrate-dependent methanotrophic bacteria, thereby enhancing their capacity for simultaneous nitrogen and carbon removal. Our findings reveal that iron may act as a metabolic "switch" in microorganisms, offering new insights into the targeted manipulation of microbial metabolism to maximize their beneficial functions in both engineered and natural environments.

Iron modulates barrier integrity and stem cell function of small intestine during experimental colitis

Background

Ulcerative colitis (UC) brings inconvenience to many patients with inflammatory bowel disease (IBD). Although colonic pathology is widely investigated, little attention has been paid to the disorders in small intestine of UC. In this study, we investigated the impairments of UC to small intestine and further explored how iron metabolism regulated epithelial integrity and the activity of intestinal stem cells (ISCs).

Methods

Mice were treated by 2.5% dextran sulfate sodium (DSS) for 7 days to established acute experimental colitis. Small intestinal tissues were collected at different time points in the process of DSS-induced colitis. Histological analysis was used to evaluate the changes of small intestine, including H&E, Alcian blue and PAS staining, immunostaining, and qRT-PCR. Iron content was modulated by the supplementation of ferric citrate or depletion by deferoxamine (DFO). The influence of iron on the barrier integrity and stem cell function was further determined by histology, IEC-6 cell, and enteroid culture. ROS content was demonstrated by DHE staining. The proliferation of intestinal stem cells (ISCs) was shown by BrdU and Olfm4 staining, and Lgr5-tdTomato mice were used for lineage tracing study.

Results

It was shown that during DSS-induced colitis, small intestine underwent a serious injury process, including dysregulated integrity and decreased proliferation of ISCs. Iron overload significantly exacerbated intestinal injury in tissues, epithelial cell line, and intestinal organoids. However, iron chelation by deferoxamine (DFO) would greatly suppress small intestinal injury. Mechanistically, iron overload exacerbated the generation of ROS and enhanced the infiltration of immune cells. In addition, STAT3 and ERK pathways in intestinal epithelium were impaired during experimental colitis, and iron content significantly interrupted the expression of p-STAT3 and p-ERK1/2 within small intestine.

Conclusion

In summary, this study proved that small intestine was also impaired in experimental colitis, and iron content could affect DSS-induced small intestinal damage and regeneration, indicating the strategy of iron supplementation in clinical practice needs to be more cautious and consider more factors.

Enhanced methanogenesis of wastewater anaerobic digestion by nanoscale zero-valent iron: Mechanism on intracellular energy conservation and amino acid metabolism

Nanoscale zero-valent iron (nZVI)-mediated anaerobic digestion commonly focuses on electron transfer between syntrophic bacteria, neglecting intracellular energy conservation strategies and amino acid metabolism. In this study, F420H2 dehydrogenase abundance increased by 5.1 %, 27.0 %, and 31.5 % at 10 mM, mM， 30 mM, and 50 mM nZVI dosing, respectively, enabling an efficient transmembrane proton-coupled electron transfer mode. Electron bifurcation (EB) enzymes involved in methanogenesis responded differently to nZVI, with HdrA2B2C2 initially increasing at 10 mM and decreasing at 30 mM and 50 mM, while MvhADG-HdrABC was completely down-regulated. Metabolomics further demonstrated that nZVI reduced riboflavin and flavin mononucleotide content, which is detrimental to the EB. Instead, an alternative measure to maintain electron flow and energy conservation under high nZVI exposure is high expression of ndh and F-type or V/A-type ATPase genes. Additionally, enhancing C1-unit carrier expression through amino acid metabolism regulation emerged as a key strategy. This study provides new perspectives on nZVI-mediated anaerobic digestion.

Cytolethal distending toxin from Glaesserella parasuis induces ferroptosis in porcine alveolar macrophages and mice

Glaesserella parasuis cytolethal distending toxin (GpCDT) is a bacterial genotoxin whose main action is to activate DNA damage responses, induce cell cycle arrest, and induce the apoptosis of host cells. In our previous studies, we reported that cells incubated with GpCDT exhibited changes in the expression of ferroptosis-related proteins; thus, we hypothesized that, in addition to apoptosis, GpCDT may also cause ferroptosis, a novel mode of cell death. Here, we observed that treatment of 3D4/21 cells with GpCDT resulted in cytoplasmic iron overload, depletion of GSH (reduced glutathione), and overproduction of reactive oxygen species (ROS) and malondialdehyde (MDA), indicating that GpCDT disrupted iron metabolism and redox homeostasis in these cells. These phenomena were counteracted by the specific ferroptosis inhibitor ferrostatin-1 and the iron chelator deferoxamine mesylate. In vitro infection with the Glaesserella parasuis field isolate strain SC1401 (CDT positive) induced changes in the expression of ferroptosis biomarkers and proteins. Infection of C57BL/6 mice yielded similar results. Our results suggest that ferroptosis may play a substantial role in GpCDT-induced cellular injury.

A systematical review on traditional Chinese medicine treating chronic diseases via regulating ferroptosis from the perspective of experimental evidence and clinical application

Ferroptosis is a unique regulated form of cell death that is distinct from apoptosis, necrosis, and other well-characterized regulated cell death types, and plays an important role in the occurrence and development of chronic metabolic diseases, including diabetes, hypertension, hyperlipidemia, and non-alcoholic steatohepatitis. Recently, increasing evidence has supported traditional Chinese medicine (TCM) as a new hot spot for the treatment of chronic metabolic diseases by mediating ferroptosis. Unfortunately, few systematic reviews have described the importance of TCM in treating chronic metabolic diseases through the ferroptosis pathway. In the current review, the mechanism of ferroptosis and the roles of ferroptosis in chronic metabolic diseases are summarized. Additionally, this review illustrates that the regulation of ferroptosis by TCM could be an effective approach for treating chronic metabolic diseases based on experimental evidence and clinical application. In summary, this work will improve the understanding of ferroptosis and the ability of TCM to regulate ferroptosis in chronic metabolic diseases, thereby promoting the development and application of natural TCM.

The impact of gut microbiota on the occurrence, treatment, and prognosis of ischemic stroke

Ischemic stroke (IS) is a cerebrovascular disease that predominantly affects middle-aged and elderly populations, exhibiting high mortality and disability rates. At present, the incidence of IS is increasing annually, with a notable trend towards younger affected individuals. Recent discoveries concerning the "gut-brain axis" have established a connection between the gut and the brain. Numerous studies have revealed that intestinal microbes play a crucial role in the onset, progression, and outcomes of IS. They are involved in the entire pathophysiological process of IS through mechanisms such as chronic inflammation, neural regulation, and metabolic processes. Although numerous studies have explored the relationship between IS and intestinal microbiota, comprehensive analyses of specific microbiota is relatively scarce. Therefore, this paper provides an overview of the typical changes in gut microbiota following IS and investigates the role of specific microorganisms in this context. Additionally, it presents a comprehensive analysis of post-stroke microbiological therapy and the relationship between IS and diet. The aim is to identify potential microbial targets for therapeutic intervention, as well as to highlight the benefits of microbiological therapies and the significance of dietary management. Overall, this paper seeks to provide key strategies for the treatment and management of IS, advocating for healthy diets and health programs for individuals. Meanwhile, it may offer a new perspective on the future interdisciplinary development of neurology, microbiology and nutrition.

Comprehensive genomic epidemiology and antimicrobial resistance profiles of clinical Klebsiella pneumoniae species complex isolates from a tertiary hospital in Wenzhou, China (2019-2021)

BACKGROUND

The main issue of the Klebsiella pneumoniae species complex (KpSC) research in clinical settings is the accurate identification and differentiation of the closely related species within this complex. Moreover, the emergence and spread of carbapenem-resistant K. pneumoniae (CRKP) represent a significant public health threat due to limited treatment options and high mortality rates. Understanding the genetic basis of resistance and virulence is crucial for developing effective infection control strategies. In this work, the genomic epidemiology and antimicrobial resistance profile of KpSC isolates from Wenzhou, China, was investigated to fully understand the implications of the KpSC in clinical settings.

METHODS

We conducted a comprehensive analysis of 156 clinical KpSC isolates collected from a tertiary hospital in China over a three-year period (2019-2021). Antimicrobial susceptibility testing was performed according to CLSI standards. Whole-genome sequencing (WGS) and subsequent bioinformatic analyses were conducted to identify resistance genes, plasmid types, and virulence factors. Phylogenetic relationships were determined using maximum-likelihood analysis.

RESULTS

All CRKP isolates exhibited high levels of resistance to carbapenems, cephalosporins, and aminoglycosides. The most prevalent carbapenemase genes were blaKPC-2 (100%), with significant associations between blaKPC-2 and ST11. Phylogenetic analysis revealed considerable genetic diversity, with over 50 sequence types (STs) present. A subset of isolates harbored both resistance and hypervirulence genes, including rmpA, rmpA2, and siderophore systems, which were associated with potential higher pathogenesis.

CONCLUSION

This study provides novel insights into the molecular epidemiology of KpSC in Wenzhou, China, highlighting the coexistence of antimicrobial resistance and virulence factors in clinical isolates. The findings underscore the importance of continuous genomic surveillance and targeted therapeutic strategies to combat KpSC infections. Our research fills critical gaps in the current understanding of KpSC epidemiology in China and offers valuable data for global comparative studies, contributing to the development of effective infection control measures. Genomic surveillance in China thus provides crucial insights for local risk mapping and informs necessary adaptions for implementation of control strategies.

Protein absorption in the zebrafish gut is regulated by interactions between lysosome rich enterocytes and the microbiome

Dietary protein absorption in neonatal mammals and fishes relies on the function of a specialized and conserved population of highly absorptive lysosome-rich enterocytes (LREs). The gut microbiome has been shown to enhance absorption of nutrients, such as lipids, by intestinal epithelial cells. However, whether protein absorption is also affected by the gut microbiome is poorly understood. Here, we investigate connections between protein absorption and microbes in the zebrafish gut. Using live microscopy-based quantitative assays, we find that microbes slow the pace of protein uptake and degradation in LREs. While microbes do not affect the number of absorbing LRE cells, microbes lower the expression of endocytic and protein digestion machinery in LREs. Using transgene-assisted cell isolation and single cell RNA-sequencing, we characterize all intestinal cells that take up dietary protein. We find that microbes affect expression of bacteria-sensing and metabolic pathways in LREs, and that some secretory cell types also take up protein and share components of protein uptake and digestion machinery with LREs. Using custom-formulated diets, we investigated the influence of diet and LRE activity on the gut microbiome. Impaired protein uptake activity in LREs, along with a protein-deficient diet, alters the microbial community and leads to an increased abundance of bacterial genera that have the capacity to reduce protein uptake in LREs. Together, these results reveal that diet-dependent reciprocal interactions between LREs and the gut microbiome regulate protein absorption.

The Microbiota and Evolution of Obesity

Obesity is a major global concern and is generally attributed to a combination of genetic and environmental factors. Several hypotheses have been proposed to explain the evolutionary origins of obesity epidemic, including thrifty and drifty genotypes, and changes in thermogenesis. Here, we put forward the hypothesis of metaflammation, which proposes that due to intense selection pressures exerted by environmental pathogens, specific genes that help develop a robust defense mechanism against infectious diseases have had evolutionary advantages and that this may contribute to obesity in modern times due to connections between the immune and energy storage systems. Indeed, incorporating the genetic variations of gut microbiota into the complex genetic framework of obesity makes it more polygenic than previously believed. Thus, uncovering the evolutionary origins of obesity requires a multifaceted approach that considers the complexity of human history, the unique genetic makeup of different populations, and the influence of gut microbiome on host genetics.

Causal Relationships Between Iron Deficiency Anemia, Gut Microbiota, and Metabolites: Insights from Mendelian Randomization and In Vivo Data

Background: Iron deficiency anemia (IDA) is a common type of anemia in children and pregnant women. The effects of iron deficiency on gut microbiota and metabolic profiles are not fully understood. Methods: Mendelian randomization (MR) analysis was conducted to explore associations among IDA, gut microbiota, and metabolites. MR analysis was conducted using computational methods, utilizing human genetic data. Data were obtained from genome-wide association studies (GWAS), with inverse-variance-weighted (IVW) as the primary method. Animal models evaluated the effects of IDA on gut microbiota and metabolic profiles. Results: IVW analysis revealed significant associations between gut microbial taxa and IDA. The genus Desulfovibrio was protective (OR = 0.85, 95% CI: 0.77-0.93, p = 0.001), while Actinomyces (OR = 1.12, 95% CI: 1.01-1.23, p = 0.025) and family XIII (OR = 1.16, 95% CI: 1.01-1.32, p = 0.035) increased IDA risk. Glycine was protective (OR = 0.95, 95% CI: 0.91-0.99, p = 0.011), whereas medium low density lipoprotein (LDL) phospholipids increased risk (OR = 1.07, 95% CI: 1.00-1.15, p = 0.040). Animal models confirmed reduced Desulfovibrio, increased Actinomyces, and altered metabolites, including amino acids and phospholipids. Conclusions: IDA significantly impacts gut microbiota and metabolic profiles, offering insights for therapeutic strategies targeting microbiota and metabolism.

The Gut Microbiota Metabolite Butyrate Modulates Acute Stress-Induced Ferroptosis in the Prefrontal Cortex via the Gut-Brain Axis

Stress has been implicated in the onset of mental disorders such as depression, with the prefrontal cortex (PFC) playing a crucial role. However, the underlying mechanisms remain to be fully elucidated. Metabolites secreted by intestinal flora can enter the bloodstream and exert regulatory effects on the body. Consequently, this study aims to investigate the molecular mechanisms by which gut flora influences ferroptosis in PFC neurons, thereby affecting depression-like behavioral changes in mice subjected to acute stress. Initially, we established a mouse model of acute restraint stress (3-day duration) and verified that stress-induced ferroptosis of PFC neurons contributed to depression-like behavioral alterations in mice, as evidenced by morphological, behavioral, and molecular biology assessments. Subsequently, through fecal microbiota transplantation (FMT) experiments, we established a significant correlation between gut microbiota and ferroptosis of PFC neurons in acute stress-exposed mice. 16S rDNA sequencing identified butyric acid-producing bacteria, specifically g_Butyricimonas and its primary metabolite, butyric acid, as critical regulators of ferroptosis in PFC neurons in acutely stressed mice. Furthermore, the intervention of butyrate demonstrated its potential to ameliorate damage to the intestinal and blood-brain barriers in these mice. This intervention also mitigated depression-like behaviors induced by ferroptosis of PFC neurons by alleviating systemic inflammatory responses. The findings of this study indicate that acute stress-induced ferroptosis of PFC neurons plays a critical role in depression-like behavioral changes in mice. Additionally, the gut microbiota metabolite butyrate can modulate ferroptosis and depression-like behavioral changes through the gut-brain axis.

Targeting ion homeostasis in metabolic diseases: Molecular mechanisms and targeted therapies

The incidence of metabolic diseases-hypertension, diabetes, obesity, metabolic dysfunction-associated steatotic liver disease (MASLD), and atherosclerosis-is increasing annually, imposing a significant burden on both human health and the social economy. The occurrence and development of these diseases are closely related to the disruption of ion homeostasis, which is crucial for maintaining cellular functions and metabolic equilibrium. However, the specific mechanism of ion homeostasis in metabolic diseases is still unclear. This article reviews the role of ion homeostasis in the pathogenesis of metabolic diseases and assesses its potential as a therapeutic target. Furthermore, the article explores pharmacological strategies that target ion channels and transporters, including existing drugs and emerging drugs under development. Lastly, the article discusses the development direction of future therapeutic strategies, including the possibility of gene therapy targeting specific ion channels and personalized therapy using novel biomarkers. In summary, targeting ion homeostasis provides a new perspective and potential therapeutic approach for the treatment of metabolic diseases.

Gut Microbiota: An Important Participant in Childhood Obesity

Increasing prevalence of childhood obesity has emerged as a critical global public health concern. Recent studies have challenged the previous belief that obesity was solely a result of excessive caloric intake. Alterations in early-life gut microbiota can contribute to childhood obesity through their influence on nutrient absorption and metabolism, initiation of inflammatory responses, and regulation of gut-brain communication. The gut microbiota is increasingly acknowledged to play a crucial role in human health, as certain beneficial bacteria have been scientifically proven to possess the capacity to reduce body fat content and enhance intestinal barrier function and their metabolic products to exhibit anti-inflammatory effect. Examples of such microbes include bifidobacteria, Akkermansia muciniphila, and Lactobacillus reuteri. In contrast, an increase in Enterobacteriaceae and propionate-producing bacteria (Prevotellaceae and Veillonellaceae) has been implicated in the induction of low-grade systemic inflammation and disturbances in lipid metabolism, which can predispose individuals to obesity. Studies have demonstrated that modulating the gut microbiota through diet, lifestyle changes, prebiotics, probiotics, or fecal microbiota transplantation may contribute to gut homeostasis and the management of obesity and its associated comorbidities. This review aimed to elucidate the impact of alterations in gut microbiota composition during early life on childhood obesity and explores the mechanisms by which gut microbiota contributes to the pathogenesis of obesity and specifically focused on recent advances in using short-chain fatty acids for regulating gut microbiota and ameliorating obesity. Additionally, it aimed to discuss the therapeutic strategies for childhood obesity from the perspective of gut microbiota, aiming to provide a theoretical foundation for interventions targeting pediatric obesity based on gut microbiota.

Plant exudates-driven microbiome recruitment and assembly facilitates plant health management

Plant-microbiome symbiotic interactions play a crucial role in regulating plant health and productivity. To establish symbiotic relationships, the plant secretes a variety of substances to facilitate microbial community recruitment and assembly. In recent years, important progress has been made in studying how plant exudates attract beneficial microorganisms and regulate plant health. However, the mechanisms of plant exudates-mediated microbial community recruitment and assembly and their effects on plant health are no comprehensive review. Here, we summarize the interaction mechanisms among plant exudates, microbial community recruitment and assembly, and plant health. First, we systematically evaluate the type and distribution of plant exudates, as well as their role in microbiome recruitment and assembly. Second, we summarize the mechanisms of plant exudates in terms of microbiome recruitment, diversity regulation and chemotaxis. Finally, we list some typical examples for elucidating the importance of plant exudates in promoting plant health and development. This review contributes to utilizing plant exudate or beneficial microbiome resources to manage plant health and productivity.

Iron Homeostasis Dysregulation, Oro-Gastrointestinal Microbial Inflammatory Factors, and Alzheimer's Disease: A Narrative Review

Alzheimer's disease (AD), the most common form of dementia, is a progressive neurodegenerative disorder that profoundly impacts cognitive function and the nervous system. Emerging evidence highlights the pivotal roles of iron homeostasis dysregulation and microbial inflammatory factors in the oral and gut microbiome as potential contributors to the pathogenesis of AD. Iron homeostasis disruption can result in excessive intracellular iron accumulation, promoting the generation of reactive oxygen species (ROS) and oxidative damage. Additionally, inflammatory agents produced by pathogenic bacteria may enter the body via two primary pathways: directly through the gut or indirectly via the oral cavity, entering the bloodstream and reaching the brain. This infiltration disrupts cellular homeostasis, induces neuroinflammation, and exacerbates AD-related pathology. Addressing these mechanisms through personalized treatment strategies that target the underlying causes of AD could play a critical role in preventing its onset and progression.

Iron-Mediated Regulation in Adipose Tissue: A Comprehensive Review of Metabolism and Physiological Effects

PURPOSE OF REVIEW

Review the latest data regarding the intersection of adipose tissue (AT) and iron to meet the needs of AT metabolism and the progression of related diseases.

RECENT FINDINGS

Iron is involved in fundamental biological metabolic processes and is precisely fine-tuned within the body to maintain cellular, tissue and even systemic iron homeostasis. AT not only serves as an energy storage depot but also represents the largest endocrine organ in the human body, maintaining systemic metabolic homeostasis. It is involved in physiological processes such as energy storage, insulin sensitivity regulation and lipid metabolism. As a unique iron-sensing tissue, AT expresses related regulatory factors, including the classic hepcidin, ferroportin (FPN), iron regulatory protein/iron responsive element (IRP/IRE) and ferritin. Consequently, the interaction between AT and iron is intricately intertwined. Imbalance of iron homeostasis produces the potential risks of steatosis, impaired glucose tolerance and insulin resistance, leading to AT dysfunction diseases, including obesity, type 2 diabetes and metabolic dysfunction-associated steatotic liver disease (MASLD). Despite the role of AT iron has garnered increasing attention in recent years, a comprehensive review that systematically organizes the connection between iron and AT remains lacking. Given the necessity of iron homeostasis, emphasizing its potential impact on AT function and metabolism regulation provides valuable insights into physiological effects such as adipocyte differentiation and thermogenesis. Futhermore, regulators including adipokines, mitochondria and macrophages have been mentioned, along with analyzing the novel perspective of iron as a key mediator influencing the fat-gut crosstalk.

Microbiome and Hemato-immune Aging

The microbiome is a highly complex and diverse symbiotic component that undergoes dynamic changes with the organismal aging. Microbial perturbations, termed dysbiosis, exert strong influence on dysregulating the bone marrow niche and subsequently promoting the aging of hematopoietic and immune system. Accumulating studies have revealed the substantial impact of intestinal microbiome on the initiation and progression of age-related hematologic alteration and diseases, such as clonal hematopoiesis and blood cancers. Current therapeutic approaches to restore the altered microbiome diversity target specific pathobionts and are demonstrated to improve clinical outcomes of antihematologic malignancy treatments. In this review, we discuss the interplay between the microbiome and the hemato-immune system during aging process. We also shed light on the emerging therapeutic strategies to tackle the dysbiosis for amelioration of aging and disease progression.

Absence of gut microbiota alleviates iron overload-induced colitis by modulating ferroptosis in mice

INTRODUCTION

Iron overload disrupts gut microbiota and induces ferroptosis, contributing to colitis. However, whether gut microbiota directly drives iron overload-induced colitis and its underlying mechanism remain unclear.

OBJECTIVES

The study aimed to explore whether gut microbiota can directly regulate iron overload-induced colitis and its underling mechanism.

METHODS

Male C57BL/6N mice were fed with ferrous sulfate to establish an iron overload model. Antibiotics and dextran sulfate sodium salt (DSS) were used to create germ-free and colitis models, respectively.

RESULTS

Results showed that iron overload caused disruption of systemic iron homeostasis via activating pro-inflammation response, which caused induction of ferroptosis and eventually resulted in colitis in mice. Notably, iron overload inhibited System Xc- and activated the nuclear factor E2-related factor 2/heme oxygenase-1 pathway, driving ferroptosis and colitis progression. Similar results were observed in mouse colon epithelial cells, which were treated with high doses ferric ammonium citrate. Additionally, iron overload exacerbated DSS-induced colitis by activating the ferroptosis and increasing harmful bacteria (e.g., Mucispirillum) abundance. Interestingly, eliminating gut microbiota attenuated iron overload-induced colitis, without affecting systemic inflammation through inhibiting ferroptosis of mice. Depletion of the gut microbiota partially mitigated the exacerbating effect of iron overload on DSS-induced colitis through inhibiting ferroptosis of mice.

CONCLUSION

Iron overload activates ferroptosis in colonic cells, increases the relative abundance of harmful bacteria, and exacerbates DSS-induced colitis in mice. Iron overload exacerbates DSS-induced ferroptosis and colitis in a microbiota-dependent manner. Targeting gut microbiota may offer new strategies for managing iron overload-induced colitis.

Protein absorption in the zebrafish gut is regulated by interactions between lysosome rich enterocytes and the microbiome

Dietary protein absorption in neonatal mammals and fishes relies on the function of a specialized and conserved population of highly absorptive lysosome rich enterocytes (LREs). The gut microbiome has been shown to enhance absorption of nutrients, such as lipids, by intestinal epithelial cells. However, whether protein absorption is also affected by the gut microbiome is poorly understood. Here, we investigate connections between protein absorption and microbes in the zebrafish gut. Using live microscopy-based quantitative assays, we find that microbes slow the pace of protein uptake and degradation in LREs. While microbes do not affect the number of absorbing LRE cells, microbes lower the expression of endocytic and protein digestion machinery in LREs. Using transgene assisted cell isolation and single cell RNA-sequencing, we characterize all intestinal cells that take up dietary protein. We find that microbes affect expression of bacteria-sensing and metabolic pathways in LREs, and that some secretory cell types also take up protein and share components of protein uptake and digestion machinery with LREs. Using custom-formulated diets, we investigated the influence of diet and LRE activity on the gut microbiome. Impaired protein uptake activity in LREs, along with a protein-deficient diet, alters the microbial community and leads to increased abundance of bacterial genera that have the capacity to reduce protein uptake in LREs. Together, these results reveal that diet-dependent reciprocal interactions between LREs and the gut microbiome regulate protein absorption.

The Parkinson's disease drug entacapone disrupts gut microbiome homoeostasis via iron sequestration

Many human-targeted drugs alter the gut microbiome, leading to implications for host health. However, the mechanisms underlying these effects are not well known. Here we combined quantitative microbiome profiling, long-read metagenomics, stable isotope probing and single-cell chemical imaging to investigate the impact of two widely prescribed drugs on the gut microbiome. Physiologically relevant concentrations of entacapone, a treatment for Parkinson's disease, or loxapine succinate, used to treat schizophrenia, were incubated ex vivo with human faecal samples. Both drugs significantly impact microbial activity, more so than microbial abundance. Mechanistically, entacapone can complex and deplete available iron resulting in gut microbiome composition and function changes. Microbial growth can be rescued by replenishing levels of microbiota-accessible iron. Further, entacapone-induced iron starvation selected for iron-scavenging gut microbiome members encoding antimicrobial resistance and virulence genes. These findings reveal the impact of two under-investigated drugs on whole microbiomes and identify metal sequestration as a mechanism of drug-induced microbiome disturbance.

Algorithm of spatial-temporal simulation for environment-strain interactions in strain-strain consortia based on resource competition mechanism

Interaction simulation for co-culture systems is important for optimizing culture conditions and improving yields. For industrial production, the environment significantly affects the spatial-temporal microbial interactions. However, the current research on polymicrobial interactions mainly focuses on interaction patterns among strains, and neglects the environment influence. Based on the resource competition relationship between two strains, this research set up the modules of cellular physicochemical properties, nutrient uptake and metabolite release, cellular survival, cell swimming and substrate diffusion, and investigated the spatial-temporal strain-environment interactions through module coupling and data mining. Furthermore, in an Escherichia coli-Saccharomyces cerevisiae consortium, the total net reproduction rate decreased as glucose was consumed. E. coli gradually dominated favorable positions due to its higher glucose utilization capacity, reaching 100 % abundance with a competitive strength of 0.86 for glucose. Conversely, S. cerevisiae decreased to 0 % abundance with a competitive strength of 0.14. The simulation results of environment influence on strain competitiveness showed that inoculation ratio and dissolved oxygen strongly influenced strain competitiveness. Specifically, strain competitiveness increased with higher inoculation ratio, whereas E. coli competitiveness increased as dissolved oxygen increased, in contrast to S. cerevisiae. On the other hand, substrate diffusion condition, micronutrients and toxins had minimal influence on strain competitiveness. This method offers a straightforward procedure without featured downscaling and provides novel insights into polymicrobial interaction simulation.

Physical Activity Reduces Metabolic Risk via Iron Metabolism: Cross-National Evidence Using the Triglyceride-Glucose Index

Purpose: Studies suggest that the triglyceride-glucose index (TyG) is a novel and comprehensive marker of metabolic health. While most research indicates that increased physical activity (PA) is linked to improved metabolic health, some studies argue that the previous markers may not fully capture this relationship. This study uses TyG as a marker of metabolic health to examine the association between PA and TyG. Methods: Data are from cross-sectional surveys in three large population studies in China and the United States: CHARLS, CHNS, and NHANES. Regression models were applied to analyze the relationship between PA and TyG, with covariates adjusted in a stepwise manner. Stratified analysis was used to explore this relationship among different population groups, and, since it has been suggested that iron metabolism plays an important role in metabolic health, it was used as a mediating variable to construct a mediation model for analysis and discussion. Results: Higher PA was significantly associated with lower TyG levels across all three databases (p < 0.001), and this relationship remained robust after full adjustment for covariates. This negative association was more pronounced in older males (over 45 years). Iron metabolism also mediated this relationship, with mediation proportions ranging from 10% to 12.5%. Conclusions: There is a significant inverse association between PA and TyG, suggesting a link between increased PA and metabolic health, with iron metabolism moderating this relationship, especially among older males.

The Role of Iron in Intestinal Mucus: Perspectives from Both the Host and Gut Microbiota

Although research on the role of iron in host immunity has a history spanning decades, it is only relatively recently that attention has been directed toward the biological effects of iron on the intestinal mucus layer, prompted by an evolving understanding of the role of this material in immune defense. The mucus layer, secreted by intestinal goblet cells, covers the intestinal epithelium, and given its unique location, interactions between the host and gut microbiota, as well as among constituent microbiota, occur frequently within the mucus layer. Iron, as an essential nutrient for the vast majority of life forms, regulates immune responses from both the host and microbial perspectives. In this review, we summarize the iron metabolism of both the host and gut microbiota and describe how iron contributes to intestinal mucosal homeostasis via the intestinal mucus layer with respect to both host and constituent gut microbiota. The findings described herein offer a new perspective on iron-mediated intestinal mucosal barrier function.

Weak magnetic field promotes denitrification by stimulating ferromagnetic ion-containing metalloprotein expression

Weak magnetic field (WMF) has been recognized to promote biological denitrification processes; however, the underlying mechanisms remain largely unexplored, hindering the optimization of its effectiveness. Here, we systematically investigated the effects of WMF on denitrification performance, enzyme activity, microbial community, and metaproteome in packed bed bioreactors treating high nitrate wastewater under different WMF intensities and C:N ratios. Results showed that WMFs significantly promoted denitrification by consistently stimulating the activities of denitrifying reductases and NAD+/NADH biosynthesis across decreasing C:N ratios. Reductases and electron transfer enzymes involved in denitrification were overproduced due to the significantly enriched overexpression of ferromagnetic ion-containing (FIC) metalloproteins. We also observed WMFs' intensity-dependent selective pressure on microbial community structures despite the effects being limited compared to those caused by changing C:N ratios. By coupling genome-centric metaproteomics and structure prediction, we found the dominant denitrifier, Halomonas, was outcompeted by Pseudomonas and Azoarcus under WMFs, likely due to its structural deficiencies in iron uptake, suggesting that advantageous ferromagnetic ion acquisition capacity was necessary to satisfy the substrate demand for FIC metalloprotein overproduction. This study advances our understanding of the biomagnetic effects in the context of complex communities and highlights WMF's potential for manipulating FIC protein-associated metabolism and fine-tuning community structure.

Non-human primate model of long-COVID identifies immune associates of hyperglycemia

Hyperglycemia, and exacerbation of pre-existing deficits in glucose metabolism, are manifestations of the post-acute sequelae of SARS-CoV-2. Our understanding of metabolic decline after acute COVID-19 remains unclear due to the lack of animal models. Here, we report a non-human primate model of metabolic post-acute sequelae of SARS-CoV-2 using SARS-CoV-2 infected African green monkeys. Using this model, we identify a dysregulated blood chemokine signature during acute COVID-19 that correlates with elevated and persistent hyperglycemia four months post-infection. Hyperglycemia also correlates with liver glycogen levels, but there is no evidence of substantial long-term SARS-CoV-2 replication in the liver and pancreas. Finally, we report a favorable glycemic effect of the SARS-CoV-2 mRNA vaccine, administered on day 4 post-infection. Together, these data suggest that the African green monkey model exhibits important similarities to humans and can be utilized to assess therapeutic candidates to combat COVID-related metabolic defects.

Probiotics functionalized with a gallium-polyphenol network modulate the intratumor microbiota and promote anti-tumor immune responses in pancreatic cancer

The intratumor microbiome imbalance in pancreatic cancer promotes a tolerogenic immune response and triggers immunotherapy resistance. Here we show that Lactobacillus rhamnosus GG probiotics, outfitted with a gallium-polyphenol network (LGG@Ga-poly), bolster immunotherapy in pancreatic cancer by modulating microbiota-immune interactions. Upon oral administration, LGG@Ga-poly targets pancreatic tumors specifically, and selectively eradicates tumor-promoting Proteobacteria and microbiota-derived lipopolysaccharides through a gallium-facilitated disruption of bacterial iron respiration. This elimination of intratumor microbiota impedes the activation of tumoral Toll-like receptors, thus reducing immunosuppressive PD-L1 and interleukin-1β expression by tumor cells, diminishing immunotolerant myeloid populations, and improving the infiltration of cytotoxic T lymphocytes in tumors. Moreover, LGG@Ga-poly hampers pancreatic tumor growth in both preventive and therapeutic contexts, and amplifies the antitumor efficacy of immune checkpoint blockade in preclinical cancer models in female mice. Overall, we offer evidence that thoughtfully designed biomaterials targeting intratumor microbiota can efficaciously augment immunotherapy for the challenging pancreatic cancer.

Alterations of gut microbiota and its metabolomics in children with 6PPDQ, PBDE, PCB, and metal(loid) exposure

The composition and metabolites of the gut microbiota can be altered by environmental pollutants. However, the effect of co-exposure to multiple pollutants on the human gut microbiota has not been sufficiently studied. In this study, gut microorganisms and their metabolites were compared between 33 children from Guiyu, an e-waste dismantling and recycling area, and 34 children from Haojiang, a healthy environment. The exposure level was assessed by estimating the daily intake (EDI) of polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), 6PPD-quinone (6PPDQ), and metal(loid)s in kindergarten dust. Significant correlations were found between the EDIs of 6PPDQ, BDE28, PCB52, Ni, Cu, and the composition of gut microbiota and specific metabolites. The Bayesian kernel machine regression model showed negative correlations between the EDIs of five pollutants (6PPDQ, BDE28, PCB52, Ni, and Cu) and the composition of gut microbiota. The EDIs of these five pollutants were positively correlated with the levels of the metabolite 2,4-diaminobutyric acid, while negatively correlated with the levels of d-erythro-sphingosine and d-threitol. Our study suggests that exposure to 6PPDQ, BDE28, PCB52, Ni, and Cu in kindergarten dust is associated with alterations in the composition and metabolites of the gut microbiota. These alterations may be associated with children's health.

The microbiota: a crucial mediator in gut homeostasis and colonization resistance

The gut microbiota is a complex and diverse community of microorganisms that colonizes the human gastrointestinal tract and influences various aspects of human health. These microbes are closely related to enteric infections. As a foreign entity for the host, commensal microbiota is restricted and regulated by the barrier and immune system in the gut and contributes to gut homeostasis. Commensals also effectively resist the colonization of pathogens and the overgrowth of indigenous pathobionts by utilizing a variety of mechanisms, while pathogens have developed strategies to subvert colonization resistance. Dysbiosis of the microbial community can lead to enteric infections. The microbiota acts as a pivotal mediator in establishing a harmonious mutualistic symbiosis with the host and shielding the host against pathogens. This review aims to provide a comprehensive overview of the mechanisms underlying host-microbiome and microbiome-pathogen interactions, highlighting the multi-faceted roles of the gut microbiota in preventing enteric infections. We also discuss the applications of manipulating the microbiota to treat infectious diseases in the gut.

Physical activity modified association of urinary metals mixture and fasting blood glucose in children: From two panel studies

There is unclear evidence available on the associations between multiple metals and fasting blood glucose (FBG) in children, and whether they could be beneficial from physical activity. We included 283 children aged 4-12 years from two panel studies with 4-consecutive morning urinary 13 essential metals and 10 non-essential metals repeated across 3 seasons. We employed multiple informant model, linear mixed-effect model, and quantile g-computation to evaluate associations of single metal and their mixture with FBG and interactions with extra-school activity. The results showed that positive relations of multiple essential metals (aluminum, chromium, copper, iron, molybdenum (Mo), nickel, selenium (Se), strontium, zinc) and non-essential metals (arsenic (As), cadmium (Cd), rubidium, titanium (Ti), thallium) with FBG were the strongest at lag 0 (the health examination day), especially in overweight & obesity children (FDR <0.05). The strongest effect presented 1-fold increment in As was related to FBG increased 1.66% (95%CI: 0.84%, 2.48%) in overweight & obesity children. Notably, modification of extra-school activity showed significant, and the effects of multiple metals on FBG were attenuated in children taking total extra-school activity ≥1 h/day, and only one type of which, low or moderate & high intensity extra-school activity reached 20 min/day (Pint <0.05). For instance, each 1-fold increased As was associated with 1.41% increased FBG in overall children taking total extra-school activity <1 h/day, while that of 0.13% in those ≥1 h/day. Meanwhile, mixture of all, essential and non-essential metals were associated with increased FBG, a trend that decreased and became nonsignificant in children having certain extra-school activity, which were dominated by Mo, Se, Ti, Cd. And such relations were substantially beneficial from extra-school activity in overweight & obesity children. Accordingly, multiple essential and non-essential metals, both individual and in mixture, were positively related to FBG in children, which might be attenuated by regular physical activity.

A Hemoglobin Bionics-Based System for Combating Antibiotic Resistance in Chronic Diabetic Wounds via Iron Homeostasis Regulation

Owing to the increased tissue iron accumulation in patients with diabetes, microorganisms may activate high expression of iron-involved metabolic pathways, leading to the exacerbation of bacterial infections and disruption of systemic glucose metabolism. Therefore, an on-demand transdermal dosing approach that utilizes iron homeostasis regulation to combat antimicrobial resistance is a promising strategy to address the challenges associated with low administration bioavailability and high antibiotic resistance in treating infected diabetic wounds. Here, it is aimed to propose an effective therapy based on hemoglobin bionics to induce disturbances in bacterial iron homeostasis. The preferred "iron cargo" is synthesized by protoporphyrin IX chelated with dopamine and gallium (PDGa), and is delivered via a glucose/pH-responsive microneedle bandage (PDGa@GMB). The PDGa@GMB downregulates the expression levels of the iron uptake regulator (Fur) and the peroxide response regulator (perR) in Staphylococcus aureus, leading to iron nutrient starvation and oxidative stress, ultimately suppressing iron-dependent bacterial activities. Consequently, PDGa@GMB demonstrates insusceptibility to genetic resistance while maintaining sustainable antimicrobial effects (>90%) against resistant strains of both S. aureus and E. coli, and accelerates tissue recovery (<20 d). Overall, PDGa@GMB not only counteracts antibiotic resistance but also holds tremendous potential in mediating microbial-host crosstalk, synergistically attenuating pathogen virulence and pathogenicity.

Redox-Regulated Iron Metabolism and Ferroptosis in Ovarian Cancer: Molecular Insights and Therapeutic Opportunities

Ovarian cancer (OC), known for its lethality and resistance to chemotherapy, is closely associated with iron metabolism and ferroptosis-an iron-dependent cell death process, distinct from both autophagy and apoptosis. Emerging evidence suggests that dysregulation of iron metabolism could play a crucial role in OC by inducing an imbalance in the redox system, which leads to ferroptosis, offering a novel therapeutic approach. This review examines how disruptions in iron metabolism, which affect redox balance, impact OC progression, focusing on its essential cellular functions and potential as a therapeutic target. It highlights the molecular interplay, including the role of non-coding RNAs (ncRNAs), between iron metabolism and ferroptosis, and explores their interactions with key immune cells such as macrophages and T cells, as well as inflammation within the tumor microenvironment. The review also discusses how glycolysis-related iron metabolism influences ferroptosis via reactive oxygen species. Targeting these pathways, especially through agents that modulate iron metabolism and ferroptosis, presents promising therapeutic prospects. The review emphasizes the need for deeper insights into iron metabolism and ferroptosis within the redox-regulated system to enhance OC therapy and advocates for continued research into these mechanisms as potential strategies to combat OC.

Characteristics of Gut Microbiota and Fecal Metabolites in Patients with Colorectal Cancer-Associated Iron Deficiency Anemia

Patients with colorectal cancer (CRC) have a high prevalence of iron deficiency anemia (IDA), and the gut microbiota is closely related to iron metabolism. We performed metagenomic and metabolomic analyses of stool samples from 558 eligible samples, including IDA CRC patients (IDA, n = 69), non-anemia CRC patients (Non-Anemia, n = 245), and healthy controls (CTRL, n = 244), to explore the dynamically altered gut microbes and their metabolites. Compared with the CTRL group, fecal bacteria in both the IDA group and the Non-Anemia group showed a decrease in alpha diversity and changes in microbial communities. Flavonifractor plautii (F. plautii) increases progressively from CTRL to Non-Anemia to IDA, accompanied by decreased trimethoxyflavanone and a downregulated KO gene, megDIII. In the Non-Anemia group, Parabacteroides showed a specifically elevated abundance positively correlated with enriched 1,25-dihydroxyvitamin D3. The intricate correlations among gut microbiota, metabolites, and KO genes were uncovered and highlighted, implicating an aberrant iron metabolism vulnerable to chronic inflammation during the deterioration of the anemic condition. Furthermore, the amount of F. plautii in feces achieved independent and effective prediction performance for the poor outcome of CRC. Perturbed host-microbe interplays represent a novel prospect for explaining the pathogenesis of CRC-associated IDA. The fecal microbial features also reflect the associations between IDA and elevated CRC recurrence risk.

Low-Iron Diet-Induced Fatty Liver Development Is Microbiota Dependent and Exacerbated by Loss of the Mitochondrial Iron Importer Mitoferrin2

Iron deficiency is the number one nutritional problem worldwide. Iron uptake is regulated at the intestine and is highly influenced by the gut microbiome. Blood from the intestines drains directly into the liver, informing iron status and gut microbiota status. Changes in either iron or the microbiome are tightly correlated with the development of metabolic dysfunction-associated steatotic liver disease (MASLD). To investigate the underlying mechanisms of the development of MASLD that connect altered iron metabolism and gut microbiota, we compared specific pathogen free (SPF) or germ-free (GF) mice, fed a normal or low-iron diet. SPF mice on a low-iron diet showed reduced serum triglycerides and MASLD. In contrast, GF low-iron diet-fed mice showed increased serum triglycerides and did not develop hepatic steatosis. SPF mice showed significant changes in liver lipid metabolism and increased insulin resistance that was dependent upon the presence of the gut microbiota. We report that total body loss of mitochondrial iron importer Mitoferrin2 (Mfrn2-/-) exacerbated the development of MASLD on a low-iron diet with significant lipid metabolism alterations. Our study demonstrates a clear contribution of the gut microbiome, dietary iron, and Mfrn2 in the development of MASLD and metabolic syndrome.

Ferroptosis resists intracellular Vibrio splendidus AJ01 mediated by ferroportin in sea cucumber Apostichopus japonicus

Ferroptosis, a kind of programmed cell death, is characterized with iron-dependent lipid ROS buildup, which is considered as an important cellular immunity in resisting intracellular bacterial infection in mammalian macrophages. In this process, lipid ROS oxidizes the bacterial biofilm to inhibit intracellular bacteria. However, the function of ferroptosis in invertebrate remains unknown. In this study, the existence of ferroptosis in Apostichopus japonicus coelomocytes was confirmed, and its antibacterial mechanism was investigated. First, our results indicated that the expression of glutathione peroxidase (AjGPX4) was significantly inhibited by 0.21-fold (p < 0.01) after injecting A. japonicus with the ferroptosis inducer RSL3, and the contents of MDA (3.93-fold, p < 0.01), ferrous iron (1.40-fold, p < 0.01), and lipid ROS (3.10-fold, p < 0.01) were all significantly increased under this condition and simultaneously accompanied with mitochondrial contraction and disappearance of cristae, indicating the existence of ferroptosis in the coelomocytes of A. japonicus. Subsequently, the contents of ferrous iron (1.40-fold, p < 0.05), MDA (2.10-fold, p < 0.01), ROS (1.70-fold, p < 0.01), and lipid ROS (2.50-fold, p < 0.01) were all significantly increased, whereas the mitochondrial membrane potential and GSH/GSSG were markedly decreased by 0.68-fold (p < 0.05) and 0.69-fold (p < 0.01) under Vibrio splendidus (AJ01) infection. This process could be reversed by the iron-chelating agent deferoxamine mesylate, which indicated that AJ01 could induce coelomocytic ferroptosis. Moreover, the results demonstrated that the intracellular AJ01 load was clearly decreased to 0.49-fold (p < 0.05) and 0.06-fold (p < 0.01) after treating coelomocytes with RSL3 and ferrous iron, which indicated that enhanced ferroptosis could inhibit bacterial growth. Finally, subcellular localization demonstrated that ferrous iron efflux protein ferroportin (AjFPN) and intracellular AJ01 were co-localized in coelomocytes. After AjFPN interference (0.58-fold, p < 0.01), the signals of ferrous iron and lipid ROS levels in intracellular AJ01 were significantly reduced by 0.38-fold (p < 0.01) and 0.48-fold (p < 0.01), indicating that AjFPN was an important factor in the introduction of ferroptosis into intracellular bacteria. Overall, our findings indicated that ferroptosis could resist intracellular AJ01 infection via AjFPN. These findings provide a novel defense mechanism for aquatic animals against intracellular bacterial infection.

Toxic effects of nanoplastics on biological nitrogen removal in constructed wetlands: Evidence from iron utilization and metabolism

Nanoplastics (NPs) in wastewaters may present a potential threat to biological nitrogen removal in constructed wetlands (CWs). Iron ions are pivotal in microbially mediated nitrogen metabolism, however, explicit evidence demonstrating the impact of NPs on nitrogen removal regulated by iron utilization and metabolism remains unclear. Here, we investigated how NPs disturb intracellular iron homeostasis, consequently interfering with the coupling mechanism between iron utilization and nitrogen metabolism in CWs. Results indicated that microorganisms affected by NPs developed a siderophore-mediated iron acquisition mechanism to compensate for iron loss. This deficiency resulted from NPs internalization limited the activity of the electron transport system and key enzymes involved in nitrogen metabolism. Microbial network analysis further suggested that NPs exposure could potentially trigger destabilization in microbial networks and impair effective microbial communication, and ultimately inhibit nitrogen metabolism. These adverse effects, accompanied by the dominance of Fe3+ over certain electron acceptors engaged in nitrogen metabolism under NPs exposure, were potentially responsible for the observed significant deterioration in nitrogen removal (decreased by 30 %). This study sheds light on the potential impact of NPs on intracellular iron utilization and offers a substantial understanding of the iron-nitrogen coupling mechanisms in CWs.

Ferroptosis: a potential bridge linking gut microbiota and chronic kidney disease

Ferroptosis is a novel form of lipid peroxidation-driven, iron-dependent programmed cell death. Various metabolic pathways, including those involved in lipid and iron metabolism, contribute to ferroptosis regulation. The gut microbiota not only supplies nutrients and energy to the host, but also plays a crucial role in immune modulation and metabolic balance. In this review, we explore the metabolic pathways associated with ferroptosis and the impact of the gut microbiota on host metabolism. We subsequently summarize recent studies on the influence and regulation of ferroptosis by the gut microbiota and discuss potential mechanisms through which the gut microbiota affects ferroptosis. Additionally, we conduct a bibliometric analysis of the relationship between the gut microbiota and ferroptosis in the context of chronic kidney disease. This analysis can provide new insights into the current research status and future of ferroptosis and the gut microbiota.

New insights into nitrogen removal by divalent iron-enhanced moving bed biofilm reactor: Performance, interfacial interaction and co-occurrence network

A divalent iron-mediated moving bed biofilm reactor with intermittent aeration was developed to enhance the nitrogen removal at low carbon-to-nitrogen ratios. The study demonstrated thatammonia removal increased from 51 ± 4 % to 79 ± 4 % and nitrate removal increased from 72 ± 5 % to 98 ± 4 % in phases I-IV, and 2-5 mg·L-1 of divalent iron significantly increased the anoxic denitrification process. Divalent iron stimulated the secretion of extracellular polymeric substances, which facilitated the formation of cross-linked network between microbial cells. Furthermore, the cycle between divalent and trivalent iron decreased the energy barrier between the biofilm and the pollutant. The microbial community further revealed that Proteobacteria (relative abundance: 40-48 %) andBacteroidota(relative abundance: 31-37 %) were the dominant phyla, supporting the synchronous nitrification and denitrification processes as well as the lower accumulation of nitrite. In conclusion, iron redox cycling significantly enhanced the nitrogen removal. This study proposes a viable strategy for the efficient treatment of nutrient wastewater.

Categorization of the effects of E. coli LF82 and mutants lacking the chuT and shuU genes on survival, the transcriptome, and metabolome in germ-free honeybee

The precise etiology of inflammatory bowel diseases (IBDs) remains elusive. The Escherichia coli strain LF82 (LF82) is known to be associated with IBD, and we hypothesized that this association may be related to the chuT and shuU genes. Here we constructed a germ-free (GF) honeybee model to investigate the effects of LF82 chuT and shuU genes on the honeybee intestine and their mechanisms. The chuT and shuU gene deletion strains LF82∆chuT and LF82∆shuU were generated by CRISPR-Cas9. These strains, together with nonpathogenic E. coli MG1655 (MG1655) and wildtype LF82, were allowed to colonize the guts of GF honeybees to establish single bacterial colonization models. Intestinal permeability was assessed following the administration of a sterile Brilliant Blue (FCF) solution. Comprehensive transcriptomic and metabolomic analyses of intestinal samples indicated that MG1655 had few disadvantageous effects on honeybees. Conversely, colonization with LF82 and its gene-deletion mutants provoked pronounced activation of genes associated with innate immune pathways, stimulated defensive responses, and induced expression of genes associated with inflammation, oxidative stress, and glycosaminoglycan degradation. Crucially, the LF82∆chuT and LF82∆shuU strains perturbed host heme and iron regulation, as well as tryptophan metabolism. These findings suggest that the deletion of chuT and shuU genes in E. coli LF82 may alleviate intestinal inflammation by partially modulating tryptophan catabolism. Our study proposes that targeting iron uptake mechanisms could be a potential strategy to mitigate the virulence of IBD-associated bacteria.

Discovery of YFJ-36: Design, Synthesis, and Antibacterial Activities of Catechol-Conjugated β-Lactams against Gram-Negative Bacteria

Cefiderocol is the first approved catechol-conjugated cephalosporin against multidrug-resistant Gram-negative bacteria, while its application was limited by poor chemical stability associated with the pyrrolidinium linker, moderate potency against Klebsiella pneumoniae and Acinetobacter baumannii, intricate procedures for salt preparation, and potential hypersensitivity. To address these issues, a series of novel catechol-conjugated derivatives were designed, synthesized, and evaluated. Extensive structure-activity relationships and structure-metabolism relationships (SMR) were conducted, leading to the discovery of a promising compound 86b (Code no. YFJ-36) with a new thioether linker. 86b exhibited superior and broad-spectrum in vitro antibacterial activity, especially against A. baumannii and K. pneumoniae, compared with cefiderocol. Potent in vivo efficacy was observed in a murine systemic infection model. Furthermore, the physicochemical stability of 86b in fluid medium at pH 6-8 was enhanced. 86b also reduced potential the risk of allergy owing to the quaternary ammonium linker. The improved properties of 86b supported its further research and development.

High-Throughput Host-Microbe Single-Cell RNA Sequencing Reveals Ferroptosis-Associated Heterogeneity during Acinetobacter baumannii Infection

Interactions between host and bacterial cells are integral to human physiology. The complexity of host-microbe interactions extends to different cell types, spatial aspects, and phenotypic heterogeneity, requiring high-resolution approaches to capture their full complexity. The latest breakthroughs in single-cell RNA sequencing (scRNA-seq) have opened up a new era of studies in host-pathogen interactions. Here, we first report a high-throughput cross-species dual scRNA-seq technology by using random primers to simultaneously capture both eukaryotic and bacterial RNAs (scRandom-seq). Using reference cells, scRandom-seq can detect individual eukaryotic and bacterial cells with high throughput and high specificity. Acinetobacter baumannii (A.b) is a highly opportunistic and nosocomial pathogen that displays resistance to many antibiotics, posing a significant threat to human health, calling for discoveries and treatment. In the A.b infection model, scRandom-seq witnessed polarization of THP-1 derived-macrophages and the intracellular A.b-induced ferroptosis-stress in host cells. The inhibition of ferroptosis by Ferrostatin-1 (Fer-1) resulted in the improvement of cell vitality and resistance to A.b infection, indicating the potential to resist related infections. scRandom-seq provides a high-throughput cross-species dual single-cell RNA profiling tool that will facilitate future discoveries in unraveling the complex interactions of host-microbe interactions in infection systems and tumor micro-environments.

Genetic- and fiber-diet-mediated changes in virulence factors in pig colon contents and feces and their driving factors

Virulence factors (VFs) are key factors for microorganisms to establish defense mechanisms in the host and enhance their pathogenic potential. However, the spectrum of virulence factors in pig colon and feces, as well as the influence of dietary and genetic factors on them, remains unreported. In this study, we firstly revealed the diversity, abundance and distribution characteristics of VFs in the colonic contents of different breeds of pigs (Taoyuan, Xiangcun and Duroc pig) fed with different fiber levels by using a metagenomic analysis. The analysis resulted in the identification of 1,236 virulence factors, which could be grouped into 16 virulence features. Among these, Taoyuan pigs exhibited significantly higher levels of virulence factors compared to Duroc pigs. The high-fiber diet significantly reduced the abundance of certain virulence factor categories, including iron uptake systems (FbpABC, HitABC) and Ig protease categories in the colon, along with a noteworthy decrease in the relative abundance of plasmid categories in mobile genetic elements (MGEs). Further we examined VFs in feces using absolute quantification. The results showed that high-fiber diets reduce fecal excretion of VFs and that this effect is strongly influenced by MGEs and short-chain fatty acids (SCFAs). In vitro fermentation experiments confirmed that acetic acid (AA) led to a decrease in the relative abundance of VFs (p < 0.1). In conclusion, our findings reveal for the first time how fiber diet and genetic factors affect the distribution of VFs in pig colon contents and feces and their driving factors. This information provides valuable reference data to further improve food safety and animal health.

Exploring the interactions between metabolic dysfunction-associated fatty liver disease and micronutrients: from molecular mechanisms to clinical applications

Metabolic (dysfunction)-associated fatty liver disease (MAFLD) has emerged as a significant global health concern, representing a major cause of liver disease worldwide. This condition spans a spectrum of histopathologic stages, beginning with simple fatty liver (MAFL), characterized by over 5% fat accumulation, and advancing to metabolic (dysfunction)-associated steatohepatitis, potentially leading to hepatocellular carcinoma. Despite extensive research, there remains a substantial gap in effective therapeutic interventions. This condition's progression is closely tied to micronutrient levels, crucial for biological functions like antioxidant activities and immune efficiency. The levels of these micronutrients exhibit considerable variability among individuals with MAFLD. Moreover, the extent of deficiency in these nutrients can vary significantly throughout the different stages of MAFLD, with disease progression potentially exacerbating these deficiencies. This review focuses on the role of micronutrients, particularly vitamins A, D, E, and minerals like iron, copper, selenium, and zinc, in MAFLD's pathophysiology. It highlights how alterations in the homeostasis of these micronutrients are intricately linked to the pathophysiological processes of MAFLD. Concurrently, this review endeavors to harness the existing evidence to propose novel therapeutic strategies targeting these vitamins and minerals in MAFLD management and offers new insights into disease mechanisms and treatment opportunities in MAFLD.

Dose-Responsive Effects of Iron Supplementation on the Gut Microbiota in Middle-Aged Women

Oral iron supplementation is the first-line treatment for addressing iron deficiency, a concern particularly relevant to women who are susceptible to sub-optimal iron levels. Nevertheless, the impact of iron supplementation on the gut microbiota of middle-aged women remains unclear. To investigate the association between iron supplementation and the gut microbiota, healthy females aged 40-65 years (n = 56, BMI = 23 ± 2.6 kg/m2) were retrospectively analyzed from the Alberta's Tomorrow Project. Fecal samples along with various lifestyle, diet, and health questionnaires were obtained. The gut microbiota was assessed by 16S rRNA sequencing. Individuals were matched by age and BMI and classified as either taking no iron supplement, a low-dose iron supplement (6-10 mg iron/day), or high-dose iron (>100 mg/day). Compositional and functional analyses of microbiome data in relation to iron supplementation were investigated using various bioinformatics tools. Results revealed that iron supplementation had a dose-dependent effect on microbial communities. Elevated iron intake (>100 mg) was associated with an augmentation of Proteobacteria and a reduction in various taxa, including Akkermansia, Butyricicoccus, Verrucomicrobia, Ruminococcus, Alistipes, and Faecalibacterium. Metagenomic prediction further suggested the upregulation of iron acquisition and siderophore biosynthesis following high iron intake. In conclusion, adequate iron levels are essential for the overall health and wellbeing of women through their various life stages. Our findings offer insights into the complex relationships between iron supplementation and the gut microbiota in middle-aged women and underscore the significance of iron dosage in maintaining optimal gut health.

Unraveling biological behavior and influence of magnetic iron-based nanoparticles in algal-bacterial systems: A comprehensive review

Magnetic iron-based nanoparticles have been found to stimulate algae growth and harvest, repair disintegrated particles and improve stability, and facilitate operation in extreme environments, which help improve the wide application of algal-bacterial technology. Nevertheless, up to now, no literature collected to systematically review the research progress of on the employment of magnetic iron-based nanoparticles in the algal-bacterial system. This review summarizes the special effects (e.g., size effect, surface effect and biological effect) and corresponding properties of magnetic iron-based nanoparticles (e.g., magnetism, adsorption, electricity, etc.), which is closely related to biological effects and algal-bacterial behaviors. Additionally, it was found that magnetic iron-based nanoparticles offer remarkable impacts on improving the growth and metabolism of algal-bacterial consortia and the mechanisms mainly include its possible iron uptake pathways in bacteria and/or algae cells, as well as the magnetic biological effect of magnetic iron-based nanoparticles on algae-bacteria growth. Furthermore, in terms of the mechanism for establishing the algae-bacteria symbiotic relationship, the most recent works reveal that the charge effect, material transfer and signal transmission of magnetic iron-based nanoparticles possess a large array of potential mechanisms by which it can affect the establishment of algal-bacterial symbiosis. This discussion is expected to promote the progress of magnetic iron-based nanoparticles, as an eco-friendly, convenient and cost-effective technology that can be applied in algal-bacterial wastewater treatment fields.

Glioma-targeted oxaliplatin/ferritin clathrate reversing the immunosuppressive microenvironment through hijacking Fe2+ and boosting Fenton reaction

Glioma is easy to develop resistance to temozolomide (TMZ). TMZ-resistant glioma secretes interleukin-10 (IL-10) and transforming growth factor-β (TGF-β), recruiting regulatory T cell (Treg) and inhibiting the activity of T cells and natural killer cell (NK cell), subsequently forming an immunosuppressive microenvironment. Oxaliplatin (OXA) greatly inhibits the proliferation of TMZ-resistant glioma cells, but the ability of OXA to cross blood-brain barrier (BBB) is weak. Thus, the therapeutic effect of OXA on glioma is not satisfactory. Transferrin receptor 1 (TfR1) is highly expressed in brain capillary endothelial cells and TMZ-resistant glioma cells. In this study, OXA was loaded into ferritin (Fn) to prepare glioma-targeted oxaliplatin/ferritin clathrate OXA@Fn. OXA@Fn efficiently crossed BBB and was actively taken up by TMZ-resistant glioma cells via TfR1. Then, OXA increased the intracellular H2O2 level and induced the apoptosis of TMZ-resistant glioma cells. Meanwhile, Fn increased Fe2+ level in TMZ-resistant glioma cells. In addition, the expression of ferroportin 1 was significantly reduced, resulting in Fe2+ to be locked up inside the TMZ-resistant glioma cells. This subsequently enhanced the Fenton reaction and boosted the ferroptosis of TMZ-resistant glioma cells. Consequently, T cell mediated anti-tumor immune response was strongly induced, and the immunosuppressive microenvironment was significantly reversed in TMZ-resistant glioma tissue. Ultimately, the growth and invasion of TMZ-resistant glioma was inhibited by OXA@Fn. OXA@Fn shows great potential in the treatment of TMZ-resistant glioma and prospect in clinical transformation.