HMOX1 as a marker of iron excess-induced adipose tissue dysfunction, affecting glucose uptake and respiratory capacity in human adipocytes

Exploring the Efficacy and Target Genes of Atractylodes Macrocephala Koidz Against Alzheimer's Disease Based on Multi-Omics, Computational Chemistry, and Experimental Verification

OBJECTIVE

To unveil the efficacy and ferroptosis-related mechanisms of Atractylodes Macrocephala Koidz (AMK) against Alzheimer's disease (AD), which is the most widespread neurodegenerative disease.

METHODS

Gene set variation analysis (GSVA) scores were used to investigate the relationship between ferroptosis and AD. Logistic regression with seven feature selections and a deep learning model were utilized to identify potential targets of AMK based on transcriptomic data from multiple tissues. A transcriptome-wide association study (TWAS), summary-data-based mendelian randomization (SMR), and mendelian randomization (MR) were utilized to validate the causal relationship between target genes and AD risk. A single-gene gene set enrichment analysis (GSEA) was employed to investigate the biological pathways associated with the target genes. Three molecular docking strategies and a molecular dynamics simulation were employed to verify the binding domains interacting with AMK. Furthermore, the anti-AD effects of AMK were validated in a zebrafish AD model by testing behavior responses, apoptosis, and the deposition of beta-amyloid (Aβ) in the brain. Ultimately, real-time qPCR was used to verify the ferroptosis-related targets, which was identified via multi-omics.

RESULTS

Ferroptosis is an important pathogenic mechanism of AD, as suggested by the GSVA scores. AMK may exert its anti-AD activity through targets genes identified in the brain (ATP5MC3, GOT1, SAT1, EGFR, and MAPK9) and blood (G6PD, PGD, ALOX5, HMOX1, and ULK1). EGFR and HMOX1 were further confirmed as target genes mediating the anti-AD activity of AMK through TWAS, SMR, and MR analyses. The GSEA results indicated that EGFR may be involved in oxidative phosphorylation-related pathways, while HMOX1 may be associated with lysosome and phagosome pathways. The results of three molecular docking strategies and molecular dynamics simulations implied that the kinase domain of EGFR and the catalytic domain of HMOX1 played pivotal roles in the interaction between AMK and the targets. In a zebrafish model, AD-like symptoms including motor slowness and delayed responses, neuronal apoptosis, and plaque deposition in the brain, were significantly improved after AMK treatment. Accordingly, AMK reversed the abnormal expression of egfra and hmox1a, two core targets genes involved in ferroptosis.

CONCLUSIONS

AMK significantly alleviated AD-like symptoms through the modulation of EGFR and HMOX1, which might reduce lipid peroxidation, thereby suppressing ferroptosis. This study provided evidence supporting the efficacy and therapeutic targets associated with ferroptosis in AMK-treated AD, which aid in the development of therapeutic interventions.

Heme oxygenase, biliverdin reductase, and bilirubin pathways regulate oxidative stress and insulin resistance: a focus on diabetes and therapeutics

Metabolic and insulin-resistant diseases, such as type 2 diabetes mellitus (T2DM), have become major health issues worldwide. The prevalence of insulin resistance in the general population ranges from 15.5% to 44.6%. Shockingly, the global T2DM population is anticipated to double by 2050 compared with 2021. Prior studies indicate that oxidative stress and inflammation are instrumental in causing insulin resistance and instigating metabolic diseases. Numerous methods and drugs have been designed to combat insulin resistance, including metformin, thiazolidinediones (TZDs), sodium-glucose cotransporter 2 inhibitors (SGLT2i), glucagon-like peptide 1 receptor agonists (GLP1RA), and dipeptidyl peptidase 4 inhibitors (DPP4i). Bilirubin is an antioxidant with fat-burning actions by binding to the PPARα nuclear receptor transcription factor, improving insulin sensitivity, reducing inflammation, and reversing metabolic dysfunction. Potential treatment with antioxidants like bilirubin and increasing the enzyme that produces it, heme oxygenase (HMOX), has also gained attention. This review discusses the relationships between bilirubin, HMOX, and insulin sensitivity, how T2DM medications affect HMOX levels and activity, and potentially using bilirubin nanoparticles to treat insulin resistance. We explore the sex differences between these treatments in the HMOX system and how bilirubin levels are affected. We discuss the emerging concept that bilirubin bioconversion to urobilin may have a role in metabolic diseases. This comprehensive review summarizes our understanding of bilirubin functioning as a hormone, discusses the HMOX isoforms and their beneficial mechanisms, analyzes the sex differences that might cause a dichotomy in responses, and examines the potential use of HMOX and bilirubin nanoparticle therapies in treating metabolic diseases.

High expression levels of haem oxygenase-1 promote ferroptosis in macrophage-derived foam cells and exacerbate plaque instability

Plaque rupture with consequent thrombosis is the leading cause of acute cardiovascular events, during which macrophage death is a hallmark. Ferroptosis is a pivotal intermediate link between early and advanced atherosclerosis. Existing evidence indicates the involvement of macrophage ferroptosis in plaque vulnerability; however, the exact mechanism remains elusive. The aim of this study was to explore key ferroptosis-related genes (FRGs) involved in plaque progression and the underlying molecular mechanisms involved. The expression landscape of FRGs was obtained from atherosclerosis-related GEO datasets. Molecular mechanism studies of ferroptosis were performed using bone marrow-derived macrophages (BMDMs) and macrophage-derived foam cells (MDFCs). Bioinformatics analysis and immunohistochemistry revealed that macrophage haem oxygenase-1 (HMOX1) is the key FRG involved in plaque destabilization. Hypoxic conditions induced a significant increase in Hmox1 expression in MDFCs but not in macrophages. In addition, the beneficial or deleterious effects of Hmox1 were dependent on the degree of Hmox1 induction. Hmox1 overexpression drove inflammatory responses and ferroptotic oxidative stress in MDFCs and aggravated the plaque burden in atherosclerotic model mice. Further mechanistic investigations demonstrated that hypoxia-mediated degradation of egl-9 family hypoxia-inducible factor 3 (Egln3) stabilized Hif1a, which subsequently promoted Hmox1 transcription. Our findings suggest that high Hmox1 expression under hypoxia is deleterious to MDFC viability and plaque stability, providing a reference for the management of acute cardiovascular events.

Targeted Proteomics Reveals Functional Targets for Early Diabetes Susceptibility in Young Adults

BACKGROUND

The circulating proteome may encode early pathways of diabetes susceptibility in young adults for surveillance and intervention. Here, we define proteomic correlates of tissue phenotypes and diabetes in young adults.

METHODS

We used penalized models and principal components analysis to generate parsimonious proteomic signatures of diabetes susceptibility based on phenotypes and on diabetes diagnosis across 184 proteins in >2000 young adults in the CARDIA (Coronary Artery Risk Development in Young Adults study; mean age, 32 years; 44% women; 43% Black; mean body mass index, 25.6±4.9 kg/m2), with validation against diabetes in >1800 individuals in the FHS (Framingham Heart Study) and WHI (Women's Health Initiative).

RESULTS

In 184 proteins in >2000 young adults in CARDIA, we identified 2 proteotypes of diabetes susceptibility-a proinflammatory fat proteotype (visceral fat, liver fat, inflammatory biomarkers) and a muscularity proteotype (muscle mass), linked to diabetes in CARDIA and WHI/FHS. These proteotypes specified broad mechanisms of early diabetes pathogenesis, including transorgan communication, hepatic and skeletal muscle stress responses, vascular inflammation and hemostasis, fibrosis, and renal injury. Using human adipose tissue single cell/nuclear RNA-seq, we demonstrate expression at transcriptional level for implicated proteins across adipocytes and nonadipocyte cell types (eg, fibroadipogenic precursors, immune and vascular cells). Using functional assays in human adipose tissue, we demonstrate the association of expression of genes encoding these implicated proteins with adipose tissue metabolism, inflammation, and insulin resistance.

CONCLUSIONS

A multifaceted discovery effort uniting proteomics, underlying clinical susceptibility phenotypes, and tissue expression patterns may uncover potentially novel functional biomarkers of early diabetes susceptibility in young adults for future mechanistic evaluation.

Toxicity of Metal Oxide Nanoparticles: Looking through the Lens of Toxicogenomics

The impact of solubility on the toxicity of metal oxide nanoparticles (MONPs) requires further exploration to ascertain the impact of the dissolved and particulate species on response. In this study, FE1 mouse lung epithelial cells were exposed for 2-48 h to 4 MONPs of varying solubility: zinc oxide, nickel oxide, aluminum oxide, and titanium dioxide, in addition to microparticle analogues and metal chloride equivalents. Previously published data from FE1 cells exposed for 2-48 h to copper oxide and copper chloride were examined in the context of exposures in the present study. Viability was assessed using Trypan Blue staining and transcriptomic responses via microarray analysis. Results indicate material solubility is not the sole property governing MONP toxicity. Transcriptional signaling through the 'HIF-1α Signaling' pathway describes the response to hypoxia, which also includes genes associated with processes such as oxidative stress and unfolded protein responses and represents a conserved response across all MONPs tested. The number of differentially expressed genes (DEGs) in this pathway correlated with apical toxicity, and a panel of the top ten ranked DEGs was constructed (Hmox1, Hspa1a, Hspa1b, Mmp10, Adm, Serpine1, Slc2a1, Egln1, Rasd1, Hk2), highlighting mechanistic differences among tested MONPs. The HIF-1α pathway is proposed as a biomarker of MONP exposure and toxicity that can help prioritize MONPs for further evaluation and guide specific testing strategies.

NRF2 is essential for adaptative browning of white adipocytes

White adipose tissue browning, defined by accelerated mitochondrial metabolism and biogenesis, is considered a promising mean to treat or prevent obesity-associated metabolic disturbances. We hypothesize that redox stress acutely leads to increased production of reactive oxygen species (ROS), which activate electrophile sensor nuclear factor erythroid 2-Related Factor 2 (NRF2) that over time results in an adaptive adipose tissue browning process. To test this, we have exploited adipocyte-specific NRF2 knockout mice and cultured adipocytes and analyzed time- and dose-dependent effect of NAC and lactate treatment on antioxidant expression and browning-like processes. We found that short-term antioxidant treatment with N-acetylcysteine (NAC) induced reductive stress as evident from increased intracellular NADH levels, increased ROS-production, reduced oxygen consumption rate (OCR), and increased NRF2 levels in white adipocytes. In contrast, and in line with our hypothesis, longer-term NAC treatment led to a NRF2-dependent browning response. Lactate treatment elicited similar effects as NAC, and mechanistically, these NRF2-dependent adipocyte browning responses in vitro were mediated by increased heme oxygenase-1 (HMOX1) activity. Moreover, this NRF2-HMOX1 axis was also important for β3-adrenergic receptor activation-induced adipose tissue browning in vivo. In conclusion, our findings show that administration of exogenous antioxidants can affect biological function not solely through ROS neutralization, but also through reductive stress. We also demonstrate that NRF2 is essential for white adipose tissue browning processes.

Hepcidin deficiency in mice impairs white adipose tissue browning possibly due to a defect in de novo adipogenesis

The role of iron in the two major sites of adaptive thermogenesis, namely the beige inguinal (iWAT) and brown adipose tissues (BAT) has not been fully understood yet. Body iron levels and distribution is controlled by the iron regulatory peptide hepcidin. Here, we explored iron homeostasis and thermogenic activity in brown and beige fat in wild-type and iron loaded Hepcidin KO mice. Hepcidin-deficient mice displayed iron overload in both iWAT and BAT, and preferential accumulation of ferritin in stromal cells compared to mature adipocytes. In contrast to BAT, the iWAT of Hepcidin KO animals featured with defective thermogenesis evidenced by an altered beige signature, including reduced UCP1 levels and decreased mitochondrial respiration. This thermogenic modification appeared cell autonomous and persisted after a 48 h-cold challenge, a potent trigger of thermogenesis, suggesting compromised de novo adipogenesis. Given that WAT browning occurs in both mice and humans, our results provide physiological results to interrogate the thermogenic capacity of patients with iron overload disorders.

Apoptosis and heart failure: The role of non-coding RNAs and exosomal non-coding RNAs

Heart failure is a condition that affects the cardio vascular system and occurs if the heart cannot adequately pump the oxygen and blood to the body. Myocardial infarction, reperfusion injury, and this disease is the only a few examples of the numerous cardiovascular illnesses that are impacted by the closely controlled cell deletion process known as apoptosis. Attention has been paid to the creation of alternative diagnostic and treatment modalities for the condition. Recent evidences have shown that some non-coding RNAs (ncRNAs) influence the stability of proteins, control of transcription factors, and HF apoptosis through a variety of methods. Exosomes make a significant paracrine contribution to the regulation of illnesses as well as to the communication between nearby and distant organs. However, it has not yet been determined whether exosomes regulate the cardiomyocyte-tumor cell interaction in ischemia HF to limit the vulnerability of malignancy to ferroptosis. Here, we list the numerous ncRNAs in HF that are connected to apoptosis. In addition, we emphasize the significance of exosomal ncRNAs in the HF.

RNA N6-methyladenosine profiling reveals differentially methylated genes associated with intramuscular fat metabolism during breast muscle development in chicken

Intramuscular fat (IMF) is an important indicator for determining meat quality, and IMF deposition during muscle development is regulated by a complex molecular network involving multiple genes. The N⁶-methyladenosine (m⁶A) modification of mRNA plays an important regulatory role in muscle adipogenesis. However, the distribution of m⁶A and its role in IMF metabolism in poultry has not been reported. In the present study, a transcriptome-wide m⁶A profile was constructed using methylated RNA immunoprecipitation sequence (MeRIP-seq) and RNA sequence (RNA-seq) to explore the potential mechanism of regulating IMF deposition in the breast muscle based on the comparative analysis of IMF differences in the breast muscles of 42 (group G), 126 (group S), and 180-days old (group M) Jingyuan chickens. The findings revealed that the IMF content in the breast muscle increased significantly with the increase in the growth days of the Jingyuan chickens (P < 0.05). The m⁶A peak in the breast muscles of the 3 groups was highly enriched in the coding sequence (CDS) and 3' untranslated regions (3' UTR), which corresponded to the consensus motif RRACH. Moreover, we identified 129, 103, and 162 differentially methylated genes (DMGs) in the breast muscle samples of the G, S, and M groups, respectively. Functional enrichment analyses revealed that DMGs are involved in many physiological activities of muscle fat anabolism. The m⁶A-induced ferroptosis pathway was identified in breast muscle tissue as a new target for regulating IMF metabolism. In addition, association analysis demonstrated that LMOD2 and its multiple m⁶A negatively regulated DMGs are potential regulators of IMF differential deposition in muscle. The findings of the present study provide a solid foundation for further investigation into the potential role of m⁶A modification in regulating chicken fat metabolism.

The Effects of a Mixture of Cadmium, Lead, and Mercury on Metabolic Syndrome and Its Components, as well as Cognitive Impairment: Genes, MicroRNAs, Transcription Factors, and Sponge Relationships : The Effects of a Mixture of Cadmium, Lead, and Mercury on Metabolic Syndrome and Its Components, as well as Cognitive Impairment: Genes, MicroRNAs, Transcription Factors, and Sponge Relationships

Converging evidence indicates heavy metal-induced genes, transcription factors (TFs), and microRNAs (miRNAs) are critical pathological components of metabolic syndrome (MetS) and cognitive impairment. Thus, our goals are to identify the interaction of mixed heavy metals (cadmium + lead + mercury) with genes, TFs, and miRNAs involved in MetS and its components, as well as cognitive impairment development. The most commonly retrieved genes for each disease were different, but essential biological pathways such as oxidative stress, altered lipoprotein metabolism, fluid shear stress and atherosclerosis, apoptosis, the IL-6 signaling pathway, and Alzheimer's disease were highlighted. The genes CASP3, BAX, BCL2, IL6, TNF, APOE, HMOX1, and IGF were found to be mutually affected by the heavy metal mixture studied, suggesting the importance of apoptosis, inflammation, lipid, heme, and glucose metabolism in MetS and cognitive impairment, as well as the potentiality of targeting these genes in prospective therapeutic intervention for these diseases. EGR2, ATF3, and NFE2L2 were noted as the most key TFs implicated in the etiology of MetS and its components, as well as cognitive impairment. We also found six miRNAs induced by studied heavy metals were the mutual miRNAs linked to MetS, its components, and cognitive impairment. In particular, we used miRNAsong to construct and verify a miRNA sponge sequence for these miRNAs. These sponges are promising molecules for the treatment of MetS and its components, as well as cognitive impairment.

Iron and the Pathophysiology of Diabetes

High iron is a risk factor for type 2 diabetes mellitus (T2DM) and affects most of its cardinal features: decreased insulin secretion, insulin resistance, and increased hepatic gluconeogenesis. This is true across the normal range of tissue iron levels and in pathologic iron overload. Because of iron's central role in metabolic processes (e.g., fuel oxidation) and metabolic regulation (e.g., hypoxia sensing), iron levels participate in determining metabolic rates, gluconeogenesis, fuel choice, insulin action, and adipocyte phenotype. The risk of diabetes related to iron is evident in most or all tissues that determine diabetes phenotypes, with the adipocyte, beta cell, and liver playing central roles. Molecular mechanisms for these effects are diverse, although there may be integrative pathways at play. Elucidating these pathways has implications not only for diabetes prevention and treatment, but also for the pathogenesis of other diseases that are, like T2DM, associated with aging, nutrition, and iron.

The common genes involved in the pathogenesis of Alzheimer's disease and type 2 diabetes and their implication for drug repositioning

BACKGROUND

The prevalences of Alzheimer's disease (AD) and type 2 diabetes (T2D) continuously increase with the aging of world population. Clinical and epidemiological studies indicate that T2D is an important risk factor for AD. However, the mechanisms underlying the linkage of the two disorders are still not fully elucidated. The aim of this study is to explore the molecular mechanisms of their comorbidity and potential drug targets for AD treatment.

METHODS

We first compiled comprehensive lists of genes associated with AD and T2D, respectively. Then, we investigated the signatures of the shared genes and screened for interactions between the hub genes. Subsequently, we used Autodock Vina to perform molecular docking to predict new drug candidates. Lastly, structure and dynamics of docking results were examined by molecular dynamics simulation to verify drug reliability.

RESULTS

We obtained 917 AD-associated genes, 631 T2D-associated genes and 175 shared genes between the two disorders for subsequent analyses. Functional analysis revealed that metabolic process, lipid and atherosclerosis, AMPK signaling pathway, insulin resistance, chemokines and cytokines were enriched in the shared genes. In addition, 50 central hub genes were identified, including IL6, TNF, INS, IL1B, AKT1, VEGFA, IL10, TP53, PTGS2, TLR4, and others. Finally, we predicted new drug candidates (verdoheme and stannsoporfin) that could be potentially used for AD treatment.

CONCLUSIONS

Our study confirmed that there are important shared genes and pathways between AD and T2D, which may provide clues to reveal the molecular mechanism underlying the pathophysiology of the two diseases and help us to discover novel drug candidates for the treatment of AD. The results may also provide clues into identification of new targets and strategies for prevention and therapy of T2D that predisposes to AD.

Identification of key module and hub genes in pulpitis using weighted gene co-expression network analysis

BACKGROUND

Pulpitis is a common disease mainly caused by bacteria. Conventional approaches of diagnosing the state of dental pulp are mainly based on clinical symptoms, thereby harbor deficiencies. The accurate and rapid diagnosis of pulpitis is important for choosing the suitable therapy. The study aimed to identify pulpits related key genes by integrating micro-array data analysis and systems biology network-based methods such as weighted gene co-expression network analysis (WGCNA).

METHODS

The micro-array data of 13 inflamed pulp and 11 normal pulp were acquired from Gene Expression Omnibus (GEO). WGCNA was utilized to establish a genetic network and categorize genes into diverse modules. Hub genes in the most associated module to pulpitis were screened out using high module group members (MM) methods. Pulpitis model in rat was constructed and iRoot BP plus was applied to cap pulp. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used for validation of hub genes.

RESULTS

WGCNA was established and genes were categorized into 22 modules. The darkgrey module had the highest correlation with pulpitis among them. A total of 5 hub genes (HMOX1, LOX, ACTG1, STAT3, GNB5) were identified. RT-qPCR proved the differences in expression levels of HMOX1, LOX, ACTG1, STAT3, GNB5 in inflamed dental pulp. Pulp capping reversed the expression level of HMOX1, LOX, ACTG1.

CONCLUSION

The study was the first to produce a holistic view of pulpitis, screen out and validate hub genes involved in pulpitis using WGCNA method. Pulp capping using iRoot BP plus could reverse partial hub genes.

High-Altitude Hypoxia Exposure Induces Iron Overload and Ferroptosis in Adipose Tissue

High altitude (HA) has become one of the most challenging environments featuring hypobaric hypoxia, which seriously threatens public health, hence its gradual attraction of public attention over the past decade. The purpose of this study is to investigate the effect of HA hypoxia on iron levels, redox state, inflammation, and ferroptosis in adipose tissue. Here, 40 mice were randomly divided into two groups: the sea-level group and HA hypoxia group (altitude of 5000 m, treatment for 4 weeks). Total iron contents, ferrous iron contents, ROS generation, lipid peroxidation, the oxidative enzyme system, proinflammatory factor secretion, and ferroptosis-related biomarkers were examined, respectively. According to the results, HA exposure increases total iron and ferrous iron levels in both WAT and BAT. Meanwhile, ROS release, MDA, 4-HNE elevation, GSH depletion, as well as the decrease in SOD, CAT, and GSH-Px activities further evidenced a phenotype of redox imbalance in adipose tissue during HA exposure. Additionally, the secretion of inflammatory factors was also significantly enhanced in HA mice. Moreover, the remarkably changed expression of ferroptosis-related markers suggested that HA exposure increased ferroptosis sensitivity in adipose tissue. Overall, this study reveals that HA exposure is capable of inducing adipose tissue redox imbalance, inflammatory response, and ferroptosis, driven in part by changes in iron overload, which is expected to provide novel preventive targets for HA-related illness.

Adipose tissue macrophages exert systemic metabolic control by manipulating local iron concentrations

Iron is essential to many fundamental biological processes, but its cellular compartmentalization and concentration must be tightly controlled. Although iron overload can contribute to obesity-associated metabolic deterioration, the subcellular localization and accumulation of iron in adipose tissue macrophages is largely unknown. Here, we show that macrophage mitochondrial iron levels control systemic metabolism in male mice by altering adipocyte iron concentrations. Using various transgenic mouse models to manipulate the macrophage mitochondrial matrix iron content in an inducible fashion, we demonstrate that lowering macrophage mitochondrial matrix iron increases numbers of M2-like macrophages in adipose tissue, lowers iron levels in adipocytes, attenuates inflammation and protects from high-fat-diet-induced metabolic deterioration. Conversely, elevating macrophage mitochondrial matrix iron increases M1-like macrophages and iron levels in adipocytes, exacerbates inflammation and worsens high-fat-diet-induced metabolic dysfunction. These phenotypes are robustly reproduced by transplantation of a small amount of fat from transgenic to wild-type mice. Taken together, we identify macrophage mitochondrial iron levels as a crucial determinant of systemic metabolic homeostasis in mice.

HMOX1 silencing prevents doxorubicin-induced cardiomyocyte injury, mitochondrial dysfunction, and ferroptosis by downregulating CTGF

OBJECTIVES

Doxorubicin is a type of effective antitumor drug but can contribute to cardiomyocyte injuries. We aimed to dissect the mechanism of the HMOX1/CTGF axis in DOX-induced cardiomyocyte injury, mitochondrial dysfunction, and ferroptosis.

METHODS

Bioinformatics analysis was conducted to retrieve differentially expressed genes in a DOX-induced mouse model. Mouse cardiomyocytes, HL-1 cells, were induced with l µM DOX, after which gain- or loss-of-function assays were applied. CCK-8, fluorescent probe assay, flow cytometry, and corresponding kits were employed to detect cell viability, ROS levels, mitochondrial membrane potential and cell apoptosis, and GSH and Fe²⁺ contents, respectively. qRT-PCR or Western blot assay was adopted to test HMOX1, CTGF, BCL-2, Caspase3, Cleaved-Caspase3, and GPX4 expression.

RESULTS

Bioinformatics analysis showed that HMOX1 and CTGF were highly expressed in DOX-induced mice and correlated with each other. Also, HMOX1 and CTGF expression was high in HL-1 cells after DOX treatment, along with an obvious decrease in cell viability and GSH and GPX4 expression, an increase in ROS levels, apoptosis, and Fe²⁺ contents, and mitochondrial membrane potential dysfunction or loss. HMOX1 or CTGF silencing diminished cell apoptosis, Cleaved-Caspase3 expression, Fe²⁺ contents, and ROS levels, enhanced cell viability and the expression of GSH, GPX4, and BCL-2, and recovered mitochondrial membrane potential in DOX-induced HL-1 cells. Nevertheless, the effects of HMOX1 silencing on the viability, apoptosis, ferroptosis, and mitochondrial dysfunction of DOX-induced HL-1 cells were counteracted by CTGF overexpression.

CONCLUSIONS

In conclusion, HMOX1 silencing decreased CTGF expression to alleviate DOX-induced injury, mitochondrial dysfunction, and ferroptosis of mouse cardiomyocytes.

Adipose triglyceride lipase mediates lipolysis and lipid mobilization in response to iron-mediated negative energy balance

Maintenance of energy balance is essential for overall organismal health. Mammals have evolved complex regulatory mechanisms that control energy intake and expenditure. Traditionally, studies have focused on understanding the role of macronutrient physiology in energy balance. In the present study, we examined the role of the essential micronutrient iron in regulating energy balance. We found that a short course of dietary iron caused a negative energy balance resulting in a severe whole body wasting phenotype. This disruption in energy balance was because of impaired intestinal nutrient absorption. In response to dietary iron-induced negative energy balance, adipose triglyceride lipase (ATGL) was necessary for wasting of subcutaneous white adipose tissue and lipid mobilization. Fat-specific ATGL deficiency protected mice from fat wasting, but caused a severe cachectic response in mice when fed iron. Our work reveals a mechanism for micronutrient control of lipolysis that is necessary for regulating mammalian energy balance.

FoxO transcription factors in mitochondrial homeostasis

Mitochondria play essential roles in cellular energetics, biosynthesis, and signaling transduction. Dysfunctional mitochondria have been implicated in different diseases such as obesity, diabetes, cardiovascular disease, nonalcoholic fatty liver disease, neurodegenerative disease, and cancer. Mitochondrial homeostasis is controlled by a triad of mitochondrial biogenesis, dynamics (fusion and fission), and autophagy (mitophagy). Studies have underscored FoxO transcription factors as key mitochondrial regulators. Specifically, FoxOs regulate mitochondrial biogenesis by dampening NRF1-Tfam and c-Myc-Tfam cascades directly, and inhibiting NAD-Sirt1-Pgc1α cascade indirectly by inducing Hmox1 or repressing Fxn and Urod. In addition, FoxOs mediate mitochondrial fusion (via Mfn1 and Mfn2) and fission (via Drp1, Fis1, and MIEF2), during which FoxOs elicit regulatory mechanisms at transcriptional, posttranscriptional (e.g. via miR-484/Fis1), and posttranslational (e.g. via Bnip3-calcineurin mediated Drp1 dephosphorylation) levels. Furthermore, FoxOs control mitochondrial autophagy in the stages of autophagosome formation and maturation (e.g. initiation, nucleation, and elongation), mitochondria connected to and engulfed by autophagosome (e.g. via PINK1 and Bnip3 pathways), and autophagosome-lysosome fusion to form autolysosome for cargo degradation (e.g. via Tfeb and cathepsin proteins). This article provides an up-to-date view of FoxOs regulating mitochondrial homeostasis and discusses the potential of targeting FoxOs for therapeutics.

Serum ferritin is correlated with non-alcoholic fatty liver disease in middle-aged and older patients with type 2 diabetes

OBJECTIVE

Previous studies have shown the correlations between serum ferritin and non-alcoholic fatty liver disease (NAFLD) or diabetes. However, this relationship remains unclear in patients with type 2 diabetes (T2DM) with NAFLD. Therefore, this study aimed to elaborate the relationship between serum ferritin levels and NAFLD in middle-aged and older patients with T2DM and further explored the biomarkers for NAFLD in T2DM.

METHODS

A total of 805 middle-aged and older patients with T2DM were divided into NAFLD and non-NAFLD groups, and their serum ferritin levels were compared. Next, NAFLD group were divided into five subgroups according to the quintile levels of serum ferritin, and the differences in the constituent ratios of NAFLD were analyzed. A logistic regression analysis was performed to determine the risk factors for NAFLD in patients with T2DM.

RESULTS

The serum ferritin levels were significantly higher in T2DM patients with NAFLD (168.47 (103.78, 248.00) ng/mL) than in the non-NAFLD patients (121.19 (76.97, 208.39) ng/mL). The constituent ratios of NAFLD were significantly higher in the F5 and F4 groups than in the F2 or F1 groups (22.70 and 22.70% vs. 15.90 and 16.90%, respectively; P < 0.05). Binary logistic regression analysis showed that serum ferritin (P = 0.001) was an independent risk factor for NAFLD in patients with T2DM.

CONCLUSIONS

Serum ferritin levels were significantly increased in T2DM with NAFLD, and the constituent ratios of NAFLD increased gradually along with the increased levels of serum ferritin. Thus, serum ferritin is an independent risk factor for NAFLD in patients with T2DM.

Leptin Receptor-Deficient db/db Mice Show Significant Heterogeneity in Response to High Non-heme Iron Diet

Recent studies have shown an association between iron homeostasis, obesity and diabetes. In this work, we investigated the differences in the metabolic status and inflammation in liver, pancreas and visceral adipose tissue of leptin receptor-deficient db/db mice dependent on high iron concentration diet. 3-month-old male BKS-Leprdb/db/JOrlRj (db/db) mice were divided into two groups, which were fed with different diets containing high iron (29 g/kg, n = 57) or standard iron (0.178 g/kg; n = 42) concentrations for 4 months. As anticipated, standard iron-fed db/db mice developed obesity and diabetes. However, high iron-fed mice exhibited a wide heterogeneity. By dividing into two subgroups at the diabetes level, non-diabetic subgroup 1 (<13.5 mmol/l, n = 30) significantly differed from diabetic subgroup two (>13.5 mmol/l, n = 27). Blood glucose concentration, HbA1c value, inflammation markers interleukin six and tumor necrosis factor α and heme oxygenase one in visceral adipose tissue were reduced in subgroup one compared to subgroup two. In contrast, body weight, C-peptide, serum insulin and serum iron concentrations, pancreatic islet and signal ratio as well as cholesterol, LDL and HDL levels were enhanced in subgroup one. While these significant differences require further studies and explanation, our results might also explain the often-contradictory results of the metabolic studies with db/db mice.

Hemin attenuates response of primary rat adipocytes to adrenergic stimulation

Hemin is an activator of heme oxygenase-1 (HO-1), an enzyme catalyzing heme degradation. Up-regulation of HO-1 is observed in response to various pathological conditions. Moreover, pharmacological activation of HO-1 is associated with numerous beneficial effects in the organism. Hemin was shown to exert, among other, anti-diabetic and anti-obesity properties. These effects are strongly linked with adipose tissue. However, the direct influence of hemin on metabolism of the fat cells have not been explored. The present study aimed to determine the short-term effects of hemin on metabolism of the primary rat adipocytes. We focused on processes directly related to lipid accumulation, such as lipogenesis and lipolysis. For this purpose, the isolated cells were subjected for 2 h to 40 µM hemin, and effects of this compound on insulin-stimulated glucose conversion to lipids, lactate release, lipolysis induced by various stimuli, and also on the antilipolytic action of insulin were determined. It was shown that hemin did not affect insulin-induced lipogenesis and lactate release. However, hemin significantly decreased lipolysis stimulated by epinephrine. The inhibitory effect of hemin on epinephrine-induced lipolysis was not abolished in the presence of SnMP, an inhibitor of HO-1, which suggests hemin action irrespective of this enzyme. Similar inhibitory effects on epinephrine-induced lipolysis were observed in the presence of 3 and 12 mM glucose. Moreover, hemin was shown to reduce epinephrine-induced lipolysis also when glucose was replaced by alanine or by succinate. Apart from changes in epinephrine action, it was found that the lipolytic response of the adipocytes to isoproterenol was also diminished by hemin. However, hemin failed to affect lipolysis stimulated by dibutyryl-cAMP (a direct activator of protein kinase A), forskolin (an activator of adenylate cyclase), and also by DPCPX (an adenosine A₁ receptor antagonist). Additionally, epinephrine-induced lipolysis was shown to be decreased by insulin, and this effect was deepened in the presence of hemin. These results indicate that short-term exposure of the adipocytes to hemin does not affect processes related to glucose metabolism, such as lipogenesis and lactate release. However, hemin was found to decrease the lipolytic response to adrenergic stimulation, which is associated with reduced lipid release from adipocytes. Moreover, our results indicate that hemin is also capable of diminishing the exaggerated lipolysis, which occurs in the presence of supraphysiological concentrations of glucose.

Conserved immunomodulatory transcriptional networks underlie antipsychotic-induced weight gain

Although antipsychotics, such as olanzapine, are effective in the management of psychiatric conditions, some patients experience excessive antipsychotic-induced weight gain (AIWG). To illuminate pathways underlying AIWG, we compared baseline blood gene expression profiles in two cohorts of mice that were either prone (AIWG-P) or resistant (AIWG-R) to weight gain in response to olanzapine treatment for two weeks. We found that transcripts elevated in AIWG-P mice relative to AIWG-R are enriched for high-confidence transcriptional targets of numerous inflammatory and immunomodulatory signaling nodes. Moreover, these nodes are themselves enriched for genes whose disruption in mice is associated with reduced body fat mass and slow postnatal weight gain. In addition, we identified gene expression profiles in common between our mouse AIWG-P gene set and an existing human AIWG-P gene set whose regulation by immunomodulatory transcription factors is highly conserved between species. Finally, we identified striking convergence between mouse AIWG-P transcriptional regulatory networks and those associated with body weight and body mass index in humans. We propose that immunomodulatory transcriptional networks drive AIWG, and that these networks have broader conserved roles in whole body-metabolism.

Evaluation of the relationship between serum ferritin and insulin resistance and visceral adiposity index (VAI) in women with polycystic ovary syndrome

PURPOSE

There is a relationship between polycystic ovary syndrome (PCOS) and adipose tissue dysfunction (ADD), but this relationship is not clear. It has been recently shown that iron accumulation in adipose tissue is among the causes of adipose tissue dysfunction. Data on adipose tissue dysfunction in women with PCOS are insufficient. In this study, we aimed to evaluate the relationship between serum ferritin levels (iron accumulation biomarker) and visceral adiposity index (an indicator of adipose tissue dysfunction).

METHODS

The study is a case-control study. Women with diagnosed PCOS with 2003 Rotterdam Diagnostic Criteria (n = 40) were compared with non-PCOS group (n = 40). In this study, the cholesterol ratios, the homeostatic model evaluation index for insulin resistance (HOMA-IR) and the quantitative insulin sensitivity control index were calculated using biochemical parameters, and the visceral adiposity index (VAI) and the lipid accumulation product (LAP) were calculated using both anthropometric and biochemical parameters. In this study, insulin resistance was evaluated by HOMA-IR and adipose tissue dysfunction was evaluated by VAI index.

RESULTS

According to the results of this study, women with PCOS have a worse metabolic status than women without PCOS. However, this has been shown only in overweight and obese women, not in women with normal weight.

CONCLUSION

As a result, the presence of obesity in women with PCOS exacerbates metabolic status.

LEVEL OF EVIDENCE

Level V, cross-sectional descriptive study.

The role of iron homeostasis in adipocyte metabolism

Iron plays a vital role in the metabolism of adipose tissue. On the one hand, iron is essential for differentiation, endocrine, energy supply and other physiological functions of adipocytes. Iron homeostasis affects the progression of many chronic metabolic diseases such as obesity, type 2 diabetes mellitus, and non-alcoholic fatty liver disease. In adipose tissue, iron deficiency is associated with obesity, mainly due to inflammation. Nevertheless, excessive iron in adipose tissue leads to decreased insulin sensitivity owing to mitochondrial dysfunction and adipokine changes. On the other hand, iron has an effect on the thermogenesis of adipocytes. Iron deficiency affects the production of beige fat and the direction of the differentiation of brown fat. In this review, we summarize the current understanding of the crosstalk between iron homeostasis and metabolism in adipose tissue.

Identification of Key Pathways and Genes in Obesity Using Bioinformatics Analysis and Molecular Docking Studies

Obesity is an excess accumulation of body fat. Its progression rate has remained high in recent years. Therefore, the aim of this study was to diagnose important differentially expressed genes (DEGs) associated in its development, which may be used as novel biomarkers or potential therapeutic targets for obesity. The gene expression profile of E-MTAB-6728 was downloaded from the database. After screening DEGs in each ArrayExpress dataset, we further used the robust rank aggregation method to diagnose 876 significant DEGs including 438 up regulated and 438 down regulated genes. Functional enrichment analysis was performed. These DEGs were shown to be significantly enriched in different obesity related pathways and GO functions. Then protein-protein interaction network, target genes - miRNA regulatory network and target genes - TF regulatory network were constructed and analyzed. The module analysis was performed based on the whole PPI network. We finally filtered out STAT3, CORO1C, SERPINH1, MVP, ITGB5, PCM1, SIRT1, EEF1G, PTEN and RPS2 hub genes. Hub genes were validated by ICH analysis, receiver operating curve (ROC) analysis and RT-PCR. Finally a molecular docking study was performed to find small drug molecules. The robust DEGs linked with the development of obesity were screened through the expression profile, and integrated bioinformatics analysis was conducted. Our study provides reliable molecular biomarkers for screening and diagnosis, prognosis as well as novel therapeutic targets for obesity.

Proteomics analysis of lung reveals inflammation and cell death induced by atmospheric H2S exposure in pig

Hydrogen sulfide (H₂S) is a popular toxic environmental gas and industrial pollutant, which can be harmful to multiple organ systems of both human and livestock, especially to the respiratory system. However, the injury mechanism of H₂S exposure to lung remains poorly understood. In this study, pig lung was selected as a H₂S exposure model for the first time. We first examined the histological damage and the mRNA expression of pro-inflammatory genes of lung in pigs exposed to H₂S. Histopathology change and increased mRNA level of pro-inflammatory cytokines demonstrated that H₂S exposure indeed induced inflammatory injury in the porcine lung. We then performed TMT-based quantitative proteomics analysis to probe the injury molecular mechanism. The proteomics results showed that 526 proteins have significant changes in abundance between control and H₂S treated swine. Further validation analysis of some H₂S responsive proteins using both Real-time quantitative PCR and western blotting demonstrated that proteomics data are reliable. KEGG pathway analysis revealed that these proteins were involved in antigen processing and presentation, complement and coagulation cascade, IL-17 signaling pathway, ferroptosis and necroptosis. Our data suggest that H₂S exposure induced immune suppression, inflammatory response and cell death. These findings provide a new insight into the complexity mechanisms of H₂S induced lung injury, and offer therapeutic potential as drug targets with a view towards curing the intoxication caused by H₂S.

Transcriptional profiling of mouse cavernous pericytes under high-glucose conditions: Implications for diabetic angiopathy

Purpose

Penile erection requires integrative interactions between vascular endothelial cells, pericytes, smooth muscle cells, and autonomic nerves. Furthermore, the importance of the role played by pericytes in the pathogenesis of angiopathy has only recently been appreciated. However, global gene expression in pericytes in diabetes mellitus-induced erectile dysfunction (DMED) remains unclear. We aimed to identify potential target genes related to DMED in mouse cavernous pericytes (MCPs).

Materials and Methods

Mouse cavernous tissue was allowed to settle under gravity in collagen I-coated dishes, and sprouted cells were subcultivated for experiments. To imitate diabetic conditions, MCPs were treated with normal-glucose (NG, 5 mM) or high-glucose (HG, 30 mM) media for 3 days. Microarray technology was used to evaluate gene expression profiles, and RT-PCR was used to validate sequencing data. Histological examinations and Western blot were used to validate final selected target genes related to DMED.

Results

Decreased tube formation and increased apoptosis were detected in MCPs exposed to the HG condition. As shown by microarray analysis, the gene expression profiles of MCPs exposed to the NG or HG condition differed. A total of 2,523 genes with significantly altered expression were classified into 15 major gene categories. After further screening based on gene expression and RT-PCR and histologic results, we found that Hebp1 gene expression was significantly diminished under the HG condition and in DM mice.

Conclusions

This gene profiling study provides new potential targets responsible for diabetes in MCPs. Validation studies suggest that Hebp1 may be a suitable biomarker for DMED.

The Circular RNA CDR1as Regulates the Proliferation and Apoptosis of Human Cardiomyocytes Through the miR-135a/HMOX1 and miR-135b/HMOX1 Axes

Background: Chronic heart failure (CHF) is a major health burden worldwide, but there are a lack of effective methods for its early diagnosis and prognostic evaluation. Circular RNAs (circRNA), as a class, have been found to regulate gene expression and are implicated in multiple types of diseases. The circRNA, CDR1as, is reported to regulate gene transcription by acting as a microRNA inhibitor. However, the role of CDR1as in CHF remains to be elucidated. The aim of this study was to investigate the role and mechanism of action of the circRNA, CDR1as, in CHF. Methods: A total of 30 patients with CHF and 30 healthy persons were included in the study. The levels of CDR1as, miR-135a, and miR-135b in the plasma of all subjects were quantified by qRT-PCR. ELISA was used to detect the level of HMOX1 in plasma. The effect of CDR1as was investigated in human cardiomyocytes, including HCMs and AC16 cells. Results: CDR1as was upregulated in the plasma of patients with CHF and is a potential diagnostic marker of CHF. The levels of miR-135a and miR-135b were downregulated in the plasma of patients with CHF. The plasma level of HMOX1 in patients with CHF was significantly higher compared with the control group and was highly correlated with cardiac function in CHF patients. CDR1as was shown to act as a sponge for miR-135a and miR-135b and regulated the proliferation and apoptosis of human cardiomyocytes through the miR-135a/HMOX1 and miR-135b/HMOX1 signaling axes. Conclusion: CDR1as is a potential biomarker of CHF that is mechanistically involved in the disease pathogenesis and participates in regulating the occurrence and development of CHF through the miR-135a/HMOX1 and miR-135b/HMOX1 signaling axes.

Permanent cystathionine-β-Synthase gene knockdown promotes inflammation and oxidative stress in immortalized human adipose-derived mesenchymal stem cells, enhancing their adipogenic capacity

In the present study, we aimed to investigate the impact of permanent cystathionine-β-Synthase (CBS) gene knockdown in human telomerase reverse transcriptase (hTERT) immortalized human adipose-derived mesenchymal stem cells (ASC52telo) and in their capacity to differentiate into adipocytes. CBS gene KD in ASC52telo cells led to increased cellular inflammation (IL6, CXCL8, TNF) and oxidative stress markers (increased intracellular reactive oxygen species and decreased reduced glutathione levels) in parallel to decreased H₂S production and rejuvenation (LC3 and SIRT1)-related gene expression. In addition, CBS gene KD in ASC52telo cells resulted in altered mitochondrial respiratory function, characterised by decreased basal respiration (specifically proton leak) and spare respiratory capacity, without significant effects on cell viability and proliferation. In this context, shCBS-ASC52telo cells displayed enhanced adipogenic (FABP4, ADIPOQ, SLC2A4, CEBPA, PPARG)-, lipogenic (FASN, DGAT1)- and adipocyte (LEP, LBP)-related gene expression markers, decreased expression of proinflammatory cytokines, and increased intracellular lipid accumulation during adipocyte differentiation compared to control ASC52telo cells. Otherwise, the increased adipogenic potential of shCBS-ASC52telo cells was detrimental to the ability to differentiate into osteogenic linage. In conclusion, this study demonstrated that permanent CBS gene KD in ASC52telo cells promotes a cellular senescence phenotype with a very increased adipogenic potential, promoting a non-physiological enhanced adipocyte differentiation with excessive lipid storage.

Proteomic analysis of oxidative stress response in human umbilical vein endothelial cells (HUVECs): role of heme oxygenase 1 (HMOX1) in hypoxanthine-induced oxidative stress in HUVECs

Background

Erectile dysfunction (ED) is a well-known complication of diabetes, affecting up to 75% of diabetic men. Although the etiology of diabetic ED is multifactorial, endothelial dysfunction is considered to be a pillar of its pathophysiology. Endothelial dysfunction is caused by the harmful effects of high glucose levels and increased oxidative stress on the endothelial cells that comprise the vascular endothelium. The aim of this study was to identify the proteomic changes caused by high glucose-induced oxidative stress and explore the role of heme oxygenase 1 (HMOX1) in it.

Methods

The cellular proteomic response to hypoxanthine-induced oxidative stress in human umbilical vein endothelial cells (HUVECs) was analyzed by isobaric tags for relative and absolute quantitation (iTRAQ) combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Differentially expressed proteins (DEPs) were analyzed through Network and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. Further validation assays was performed to validate the role of HMOX1.

Results

The results showed that 66 and 76 DEPs were markedly upregulated and downregulated, respectively, for HUVECs oxidative stress. Among these proteins, we verified eight dysregulated genes by quantitative reverse transcription PCR, including nucleolin (NCL), X-ray repair cross-complementing protein 6 (XRCC6), ubiquinol-cytochrome C reductase binding protein (UQCRB), non-POU domain containing octamer binding (NONO), heme oxygenase 1 (HMOX1), nucleobindin 1 (NUCB1), DEK, and chromatin target of prmt1 (CHTOP). Further, using overexpression and genetic knockdown approaches, we found that HMOX1 was critical for the oxidative stress response in HUVECs.

Conclusions

We found that HMOX1 was closely related to the oxidative stress response induced by hypoxanthine. To the best of our knowledge, this study is the first overview of the responses of HUVECs to oxidative stress. The findings will contribute to analyses of the detailed molecular mechanisms involved in the pathogenesis of endothelial dysfunction and related molecular mechanisms in ED patients.

Hepcidin and Erythroferrone Correlate with Hepatic Iron Transporters in Rats Supplemented with Multispecies Probiotics

The influence of probiotic supplementation on iron metabolism remains poorly investigated. However, a range of studies, especially on Lactobacillus plantarum 299v (Lp229v), have indicated a possible positive impact of probiotics on iron absorption. The aim of the study was to determine the effect of multistrain probiotic supply on iron balance. Thirty Wistar rats were randomized into three groups: placebo (KK group), and multistrain probiotic per os in a daily dose of 2.5 × 10⁹ colony forming units (CFU) (PA group) or 1 × 10¹⁰ CFU (PB group). Multistrain probiotic consisted of nine bacterial strains: Bifidobacterium bifidum W23, B. lactis W51, B. lactis W52, Lactobacillus acidophilus W37, L. brevis W63, L. casei W56, L. salivarius W24, Lactococcus lactis W19, and Lc. lactis W58, in equal proportions. After six weeks, blood and organ samples were collected. No differences were found between the three groups in terms of serum concentrations of hepcidin (HEPC), lactoferrin (LTF), homocysteine (HCY), ferritin (Ft), or erythroferrone (ErFe), or in liver content of divalent metal transporter 1 (DMT1), transferrin receptors 1 and 2 (TfR), or ZRT/IRT-like protein 14 (ZIP14) proteins. In the overall sample, positive correlations were noted between the serum concentrations of hepcidin and lactoferrin, and hepcidin and ferritin; serum concentration of hepcidin and DMT1 and TfR1 in the liver; and serum concentration of erythroferrone and TfR2 in the liver. The correlations of serum hepcidin and erythroferrone with liver DMT1 and TfR represent significant mechanisms of Fe homeostasis. Our study has shown that multistrain probiotic supplementation used in the experiment did not disrupt the biochemical and hepatic regulatory processes of Fe balance and did not demonstrate significant influence on selected parameters of Fe metabolism.

Pink Urine Syndrome: A Combination of Insulin Resistance and Propofol

Pink urine syndrome is mostly seen in patients treated with propofol anesthesia. The pink color is attributed to the presence of large concentrations of uric acid (and pigment), which is excreted in large amounts when propofol is given. We describe a case of propofol-induced pink urine syndrome and perform a comprehensive, evidence-based review. We discuss prior case studies already published in the literature as we speculate on the pathophysiology and how it translates to a clinically relevant entity.

Iron metabolism gene expression and prognostic features of hepatocellular carcinoma

Iron metabolism is crucial to hepatocellular carcinoma progression and is a key determinant of prognosis. Protein-protein interactions within the iron metabolism gene network were analyzed using the European Molecular Biology Laboratory's Search Tool for Recurring Instances of Neighbouring Genes/Proteins database. We obtained 423 liver hepatocellular carcinoma gene expression profiles from the Cancer Genome Atlas database. The expression and pathway enrichment of representative iron intake genes (TFRC and DMT1), utilization genes (FTH1, FTL, HIF1A, HMOX1, SLC25A37, and SLC25A38), and efflux genes (FLVCR1 and SLC40A1) was investigated in tumor and adjacent tissues. We determined the relationship between iron metabolism and the prognostic features of liver hepatocellular carcinoma. The liver metabolism genes TFRC and FLVCR1 were related to survival, disease status, and prognosis in patients with hepatocellular carcinoma. Our results provide novel insight into liver cancer therapy.

Increased adipose tissue heme levels and exportation are associated with altered systemic glucose metabolism

Iron status is known to be associated with the physiology of adipose tissue (AT). We aimed to investigate AT heme and expression of heme exporter (FLVCR1) in association with obesity and type 2 diabetes (T2D). Substantial amounts of FLVCR1 mRNA and protein levels were detected in AT, being significantly increased in subjects with T2D, and positively correlated with fasting glucose, fasting triglycerides and with circulating markers of iron stores (serum ferritin, blood hemoglobin and hematocrit). In both visceral (VAT) and subcutaneous AT (SAT), increased heme levels were found in subjects with T2D. Reinforcing these associations, FLVCR1 mRNA levels were positively linked to fasting glucose in an independent cohort. Longitudianlly, the percent change of FLVCR1 positively correlated with the percent change in fasting glucose (r = 0.52, p = 0.03) after bariatric surgery-induced weight loss. High-fat diet-induced weight gain in rats did not result in significant changes in AT Flvcr1 mRNA but, remarkably, the expression of this gene positively correlated with fasting glucose and negatively with insulin sensitivity (QUICKI). Altogether, these findings showed a direct association between FLVCR1 mRNA levels and hyperglycemia, suggesting that increased adipose tissue heme exportation might disrupt, or is the consequence of, impaired systemic glucose metabolism during the progression to T2D.