Iron Regulation of Pancreatic Beta-Cell Functions and Oxidative Stress

Iron Regulates Cellular Proliferation by Enhancing the Expression of Glucose Transporter GLUT3 in the Liver

Iron is often accumulated in the liver during pathological conditions such as cirrhosis and cancer. Elevated expression of glucose transporters GLUT1 and GLUT3 is associated with reduced overall survival in patients with hepatocellular carcinoma. However, it is not known whether iron can regulate glucose transporters and contribute to tumor proliferation. In the present study, we found that treatment of human liver cell line HepG2 with ferric ammonium citrate (FAC) resulted in a significant upregulation of GLUT3 mRNA and protein in a dose-dependent manner. Similarly, iron accumulation in mice fed with high dietary iron as well as in mice injected intraperitoneally with iron dextran enhanced the GLUT3 expression drastically in the liver. We demonstrated that iron-induced hepatic GLUT3 upregulation is mediated by the LKB1/AMPK/CREB1 pathway, and this activation was reversed when treated with iron chelator deferiprone. In addition, inhibition of GLUT3 using siRNA prevented iron-mediated increase in the expression of cell cycle markers and cellular hyperproliferation. Furthermore, exogenous sodium beta-hydroxybutyrate treatment prevented iron-mediated hepatic GLUT3 activation both in vitro and in vivo. Together, these results underscore the importance of iron, AMPK, CREB1 and GLUT3 pathways in cell proliferation and highlight the therapeutic potential of sodium beta-hydroxybutyrate in hepatocellular carcinoma with high GLUT3 expression.

First-trimester hemoglobin, haptoglobin genotype, and risk of gestational diabetes mellitus in a retrospective study among Chinese pregnant women

BACKGROUND

This study aimed to assess whether the Haptoglobin (Hp) genotype influences the relationship between hemoglobin (Hb) levels and the development of gestational diabetes mellitus (GDM). Additionally, it sought to evaluate the interaction and joint association of Hb levels and Hp genotype with GDM risk.

METHODS

This retrospective study involved 358 women with GDM and 1324 women with normal glucose tolerance (NGT). Peripheral blood leukocytes were collected from 360 individuals at 14-16 weeks' gestation for Hp genotyping. GDM was diagnosed between 24-28 weeks' gestation. Interactive moderating effect, joint analysis, and mediation analysis were performed to evaluate the crosslink of Hb levels and Hp genotype with GDM risk.

RESULTS

Women who developed GDM had significantly higher Hb levels throughout pregnancy compared to those with NGT. Increase first-trimester Hb concentration was associated with a progressive rise in GDM incidence, glucose levels, glycosylated hemoglobin levels, Homeostasis Model Assessment for Insulin Resistance (HOMA-IR) values, cesarean delivery rates, and composite neonatal outcomes. Spline regression showed a significant linear association of GDM incidence with continuous first-trimester Hb level when the latter exceeded 122 g/L. Increased first-trimester Hb concentration was an independent risk factor for GDM development after adjusting for potential confounding factors in both the overall population and a matched case-control group. The Hp2-2 genotype was more prevalent among pregnant women with GDM when first-trimester Hb exceeded 122 g/L. Significant multiplicative and additive interactions were identified between Hb levels and Hp genotype for GDM risk, adjusted for age and pre-pregnancy BMI. The odds ratio (OR) for GDM development increased incrementally when stratified by Hb levels and Hp genotype. Moreover, first-trimester Hb level partially mediated the association between Hp genotype and GDM risk.

CONCLUSION

Increased first-trimester Hb levels were closely associated with the development of GDM and adverse pregnancy outcomes, with this association moderated by the Hp2-2 genotype.

Association between Serum Ferritin Levels and Metabolic-associated Fatty Liver Disease in Adults: a Cross-sectional Study Based on the NHANES

OBJECTIVE

Ferritin, initially acting as an iron-storage protein, was found to be associated with metabolic diseases. Our study was designed to investigate the association between serum ferritin and metabolic-associated fatty liver disease (MAFLD) using data from the National Health and Nutrition Examination Survey (NHANES) of the United State of America.

METHODS

A cross-sectional study was conducted, enrolling a total of 2145 participants from the NHANES in the 2017-2018 cycles. Hepatic steatosis and liver fibrosis were assessed by ultrasound images and several non-invasive indexes. Multiple regression analysis was conducted to determine the associations between serum ferritin concentration and MAFLD and liver fibrosis.

RESULTS

The analysis revealed that participants with higher serum ferritin levels (Q3 and Q4 groups) had a higher prevalence of MAFLD than those with the lowest serum ferritin levels [Q3 vs. Q1: OR=2.17 (1.33, 3.53), P<0.05 in fatty liver index (FLI); Q4 vs. Q1: OR=3.13 (1.91, 5.13), P<0.05 in FLI]. Additionally, participants with the highest serum ferritin levels (Q4 group) displayed a higher prevalence of liver fibrosis [Q4 vs. Q1: OR=2.59 (1.19, 5.62), P<0.05 in liver stiffness measurement; OR=5.06 (1.12, 22.94), P<0.05 in fibrosis-4 index], with significantly increased risk observed in participants with concomitant diabetes [OR=7.45 (1.55, 35.72), P=0.012].

CONCLUSION

Our study revealed that elevated serum ferritin levels are associated with a higher prevalence of MAFLD and advanced liver fibrosis in patients. Elevated serum ferritin levels combined with diabetes are important risk factors for liver fibrosis.

Iron Overload Induces Hepatic Ferroptosis and Insulin Resistance by Inhibiting the Jak2/stat3/slc7a11 Signaling Pathway

Recent studies showed that patients with iron overload had increased risk of insulin resistance or diabetes. Ferroptosis is a new type of cell death mainly caused by iron-dependent oxidative damage. In the present study, we investigated potential mechanisms of iron overload induced hepatic ferroptosis and insulin resistance through in vivo and in vitro experiments. In vivo, the mice models of iron overload were established by intraperitoneal injection of iron dextran. The changes of body weight, serum ferritin and blood glucose were measured. Hematoxylin-eosin (HE) and Perl's stainings were used to observe the pathological changes and iron deposition in the liver of mice. In vitro, HepG2 cells were treated with ferric ammonium citrate (FAC, 9 mmol/L, 24 h) to establish the cell models of iron overload. The labile iron pool, cell viability, glucose consumption and glycogen contents were measured. The ultrastructure of mitochondria was observed by transmission electron microscope (TEM). The malondialdehyde (MDA) and glutathione (GSH) kits were used to detect lipid peroxidation in liver tissues of mice and HepG2 cells. RT-PCR and Western blot were used to detect the mRNA and protein expression levels of ferroptosis factors and JAK2/STAT3 signaling pathway. In this study, we used the iron chelator deferasirox in mice and HepG2 cells. Iron overload caused weight loss, elevated serum ferritin, fasting blood glucose, fasting insulin, HOMA-IR, impaired glucose tolerance, and decreased insulin sensitivity in mice. HE staining and Perls staining showed clumps of iron deposition in the liver of iron overload mice. Iron overload could reduce the glucose consumption, increase MDA contents of HepG2 cells, while reduce glycogen and GSH contents in liver tissues of mice and HepG2 cells. TEM showed deletion of mitochondrial ridge and rupture of outer membrane in HepG2 cells with iron overload. Iron chelator deferasirox could significantly improve the above indicators, which might be related to the activation of JAK2/STAT3/SLC7A11 signaling pathway and hepatic ferroptosis. Iron overload could induce hepatic ferroptosis and insulin resistance by inhibiting the JAK2/STAT3/SLC7A11 signaling pathway, and the iron chelator deferasirox might improve hepatic insulin resistance induced by iron overload.

The complementary roles of iron and estrogen in menopausal differences in cardiometabolic outcomes

Biological hormonal changes are frequently cited as an explanatory factor of sex and menopause differences in cardiometabolic diseases (CMD) and its associated risk factors. However, iron metabolism which varies between sexes and among women of different reproductive stages could also play a role. Recent evidence suggest that iron may contribute to CMD risk by modulating oxidative stress pathways and inflammatory responses, offering insights into the mechanistic interplay between iron and CMD development. In the current review, we provide a critical appraisal of the existing evidence on sex and menopausal differences in CMD, discuss the pitfall of current estrogen hypothesis as sole explanation, and the emerging role of iron in CMD as complementary pathway. Prior to menopause, body iron stores are lower in females as compared to males, but the increase during and after menopause, is tandem with an increased CMD risk. Importantly, basic science experiments show that an increased iron status is related to the development of type 2 diabetes (T2D), and different cardiovascular diseases (CVD). While epidemiological studies have consistently reported associations between heme iron intake and some iron biomarkers such as ferritin and transferrin saturation with the risk of T2D, the evidence regarding their connection to CVD remains controversial. We delve into the factors contributing to this inconsistency, and the limitation of relying on observational evidence, as it does not necessarily imply causation. In conclusion, we provide recommendations for future studies on evaluating the potential role of iron in elucidating the sex and menopausal differences observed in CMD.

Parental obesity predisposes to exacerbated metabolic and inflammatory disturbances in childhood obesity within the framework of an altered profile of trace elements

BACKGROUND

Family history of obesity is known to increase the odds of developing childhood obesity in the offspring, but its influence in underlying molecular complications remains unexplored.

SUBJECTS/METHODS

Here, we investigated a population-based cohort comprising children with obesity, with and without parental obesity (PO+, N = 20; PO-, N = 29), and lean healthy children as controls (N = 30), from whom plasma and erythrocyte samples were collected to characterize their multi-elemental profile, inflammatory status, as well as carbohydrate and lipid metabolisms.

RESULTS

We found parental obesity to be associated with unhealthier outcomes in children, as reflected in increased blood insulin levels and reduced insulin sensitivity, unfavorable lipid profile, and pro-inflammatory milieu. This was accompanied by moderate alterations in the content of trace elements, including increased copper-to-zinc ratios and iron deficiency in circulation, as well as metal accumulation within erythrocytes.

CONCLUSIONS

Therefore, we hypothesize that family history of obesity could be an important risk factor in modulating the characteristic multi-elemental alterations behind childhood obesity, which in turn could predispose to boost related comorbidities and metabolic complications.

Toxic Metal and Essential Element Concentrations in the Blood and Tissues of Pancreatic Ductal Adenocarcinoma Patients

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive lethal neoplasm, and it has an average 5-year survival rate of less than 10%. Although the factors that influence PDAC development remain unclear, exposure to toxic metals or the imbalance in essential elements may have a role in PDAC-associated metabolic pathways.

METHODS

This study determined the concentrations of Cd, Cr, Cu, Fe, Mn, Ni, Pb, Se and Zn in whole blood, cancer and non-cancer tissues of patients affected by PDAC, and compared them with levels in healthy controls using inductively coupled plasma mass spectrometry.

RESULTS

Results of the whole blood showed significantly higher levels of Cr, Cu and Cu/Zn ratio in PDAC patients compared to the controls. In addition, the concentrations of Cu, Se, Fe and Zn significantly increased in cancer tissue compared to the healthy counterparts.

CONCLUSIONS

This study revealed evidence of altered metal levels in the blood and pancreatic tissues of PDAC patients with respect to healthy controls. These changes may contribute to multiple mechanisms involved in metal-induced carcinogenesis, including oxidative stress, DNA damage, genetic alteration, decreased antioxidant barriers and inflammatory responses. Thus, the analysis of metals can be used in the diagnosis and monitoring of PDAC neoplasms.

Dietary intakes of total, nonheme, and heme iron and hypertension risk: a longitudinal study from the China Health and Nutrition Survey

AIMS

Evidence is limited regarding the long-term impact of dietary iron intake on the development of hypertension. We investigated the association between dietary intakes of total, nonheme, and heme iron and hypertension risk in a large prospective cohort of Chinese populations over 26 years.

METHODS

A total of 16,122 adults (7810 men and 8312 women) who participated in the China Health and Nutrition Survey (1989-2015) were included. Dietary intake was repeatedly assessed by combining three consecutive 24‑h individual dietary recalls with household food inventory weighing at each survey round. Incident hypertension was defined as systolic blood pressure ≥ 140 mmHg and/or diastolic blood pressure ≥ 90 mmHg, diagnosis by physicians, or current use of anti-hypertensive drugs.

RESULTS

During a median follow‑up of 11.1 years, 2863 men and 2532 women developed hypertension. After adjustment for non-dietary and dietary factors, a lower risk of hypertension was found in men and women with higher intakes of total, nonheme, or heme iron. The adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for the highest vs. lowest quartiles were 0.76 (0.67, 0.87) in men and 0.85 (0.74, 0.97) in women for total iron intake, 0.77 (0.67, 0.87) in men and 0.85 (0.74, 0.98) in women for nonheme iron intake, and 0.73 (0.62, 0.87) in men and 0.69 (0.58, 0.82) in women for heme iron intake. Dose-response analyses further revealed a U-shaped association of total and nonheme iron intake and an L-shaped association of heme iron intake with hypertension risk in both men and women (all P for non-linearity < 0.001).

CONCLUSIONS

Our findings emphasize the importance of maintaining moderate iron intake in the prevention of hypertension. Both insufficient and excess intake of iron might increase the risk of hypertension.

The role of ferroptosis in diabetic cardiovascular diseases and the intervention of active ingredients of traditional Chinese medicine

Cardiovascular diseases (CVDs), encompassing ischaemic heart disease, cardiomyopathy, and heart failure, among others, are the most prevalent complications of diabetes and the leading cause of mortality in patients with diabetes. Cell death modalities, including apoptosis, necroptosis, and pyroptosis, have been demonstrated to be involved in the pathogenesis of CVDs. As research progresses, accumulating evidence also suggests the involvement of ferroptosis, a novel form of cell death, in the pathogenesis of CVDs. Ferroptosis, characterised by iron-dependent lipid peroxidation, which culminates in membrane rupture, may present new therapeutic targets for diabetes-related cardiovascular complications. Current treatments for CVDs, such as antihypertensive, anticoagulant, lipid-lowering, and plaque-stabilising drugs, may cause severe side effects with long-term use. Traditional Chinese medicine, with its broad range of activities and minimal side effects, is widely used in China. Numerous studies have shown that active components of Chinese medicine, such as alkaloids, polyphenols, and saponins, can prevent CVDs by regulating ferroptosis. This review summarises the recent findings on the regulatory mechanisms of active components of Chinese medicine against ferroptosis in CVDs, aiming to provide new directions and a scientific basis for targeting ferroptosis for the prevention and treatment of diabetic CVDs.

The mechanism of ferroptosis and its related diseases

Ferroptosis, a regulated form of cellular death characterized by the iron-mediated accumulation of lipid peroxides, provides a novel avenue for delving into the intersection of cellular metabolism, oxidative stress, and disease pathology. We have witnessed a mounting fascination with ferroptosis, attributed to its pivotal roles across diverse physiological and pathological conditions including developmental processes, metabolic dynamics, oncogenic pathways, neurodegenerative cascades, and traumatic tissue injuries. By unraveling the intricate underpinnings of the molecular machinery, pivotal contributors, intricate signaling conduits, and regulatory networks governing ferroptosis, researchers aim to bridge the gap between the intricacies of this unique mode of cellular death and its multifaceted implications for health and disease. In light of the rapidly advancing landscape of ferroptosis research, we present a comprehensive review aiming at the extensive implications of ferroptosis in the origins and progress of human diseases. This review concludes with a careful analysis of potential treatment approaches carefully designed to either inhibit or promote ferroptosis. Additionally, we have succinctly summarized the potential therapeutic targets and compounds that hold promise in targeting ferroptosis within various diseases. This pivotal facet underscores the burgeoning possibilities for manipulating ferroptosis as a therapeutic strategy. In summary, this review enriched the insights of both investigators and practitioners, while fostering an elevated comprehension of ferroptosis and its latent translational utilities. By revealing the basic processes and investigating treatment possibilities, this review provides a crucial resource for scientists and medical practitioners, aiding in a deep understanding of ferroptosis and its effects in various disease situations.

The Impact of Dietary Factors during Pregnancy on the Development of Islet Autoimmunity and Type 1 Diabetes: A Systematic Literature Review

AIMS AND HYPOTHESIS

The incidence of type 1 diabetes mellitus in children is considerably increasing in western countries. Thus, identification of the environmental determinants involved could ultimately lead to disease prevention. Here, we aimed to systematically review (PROSPERO ID: CRD42022362522) the current evidence of the association between maternal dietary factors during gestation and the risk of developing type 1 diabetes and/or islet autoimmunity (IA) in murine and human offspring.

METHODS

In accordance with PRISMA guidelines, the present systematic review searched PubMed and Scopus (n = 343) for different combinations of MeSH terms, such as type 1 diabetes, diet, islet autoimmunity, prenatal, nutrient, gluten, gliadin, vitamin, milk, and fibers.

RESULTS

We found that the most investigated dietary factors in the present literature were gluten, dietary advanced glycosylated end products (dAGEs), vitamin D, fatty acids, and iron. The results concerning prenatal exposure to a gluten-free environment showed a consistently protective effect on the development of IA. Prenatal exposures to vitamin D and certain fatty acids appeared to protect against the development of IA, whereas in utero iron and fat exposures correlated with increased risks of IA.

CONCLUSION

We conclude that a definite association is not established for most factors investigated as the literature represents a heterogeneous pool of data, although fetal exposures to some maternal dietary components, such as gluten, show consistent associations with increased risks of IA. We suggest that human prospective dietary intervention studies in both cohort and clinical settings are crucial to better evaluate critical and protective prenatal exposures from the maternal diet during pregnancy.

Interaction of Iron Homeostasis and Fatty Acid Metabolism in the Development of Glucose Intolerance in Women with Previous Gestational Diabetes Mellitus

A gestational diabetes mellitus (GDM) diagnosis during pregnancy means an increased risk of developing type 2 diabetes later in life. By following up with women after GDM we aimed to examine the relationship between iron parameters, individual fatty acids (FAs) and desaturases in the development of impaired glucose metabolism (IGM). Based on an oral glucose tolerance test (OGTT), six years after GDM, 157 women were grouped as having normal glucose tolerance (NGT) or IGM. Fasting serum FAs, activity of desaturases and iron parameters (ferritin, transferrin, iron, soluble transferrin receptor, total iron binding capacity, hepcidin) were measured, and clinical and anthropometric measurements taken. Soluble transferrin receptor was higher in the IGM group compared to the NGT group (3.87 vs. 3.29 mg/L, p-value = 0.023) and associated positively with saturated FAs and negatively with monounsaturated FAs in the IGM group (adjusted for BMI, age and high sensitivity C-reactive protein; p-value < 0.05). Iron, as well as transferrin saturation, showed a positive association with MUFAs and desaturase activity. These associations were not seen in the NGT group. These results suggest that iron homeostasis and FA metabolism interact in the development of glucose intolerance in women with previous GDM.

Multiple metal exposure and metabolic syndrome in elderly individuals: A case-control study in an active mining district, Northwest China

The prevalence of metabolic syndrome (MetS) is increasing at an alarming rate worldwide, particularly among elderly individuals. Exposure to various metals has been linked to the development of MetS. However, limited studies have focused attention on the elderly population living in active mining districts. Participants with MetS (N = 292) were matched for age (±2 years old) and sex with a healthy subject (N = 292). We measured the serum levels of 14 metals in older people aged 65-85 years. Conditional logistic regression, restricted cubic spline model, multiple linear regression, and Bayesian Kernel Machine Regression (BKMR) were applied to estimate potential associations between multiple metals and the risk of MetS. Serum levels of Sb and Fe were significantly higher than the controls (0.58 μg/L vs 0.46 μg/L, 2167 μg/L vs 2042 μg/L, p < 0.05), while Mg was significantly lower (20035 μg/L vs 20,394 μg/L, p < 0.05). An increased risk of MetS was associated with higher serum Sb levels (adjusted odds ratio (OR) = 1.61 for the highest tertile vs. the lowest tertile, 95% CI = 1.08-2.40, p-trend = 0.018) and serum Fe levels (adjusted OR = 1.55 for the highest tertile, 95% CI = 1.04-2.33, p-trend = 0.032). Higher Mg levels in serum may have potential protective effects on the development of MetS (adjusted OR = 0.61 for the highest tertile, 95% CI = 0.41-0.91, p-trend = 0.013). A joint exposure analysis by the BKMR model revealed that the mixture of 12 metals (except Tl and Cd) was associated with increased risk of MetS. Our results indicated that exposure to Sb and Fe might increase the risk of MetS in an elderly population living in mining-intensive areas. Further work is needed to confirm the protective effect of Mg on MetS.

Interaction Between Dietary Iron Intake and Genetically Determined Iron Overload: Risk of Islet Autoimmunity and Progression to Type 1 Diabetes in the TEDDY Study

OBJECTIVE

To examine whether iron intake and genetically determined iron overload interact in predisposing to the development of childhood islet autoimmunity (IA) and type 1 diabetes (T1D).

RESEARCH DESIGN AND METHODS

In The Environmental Determinants of Diabetes in the Young (TEDDY) study, 7,770 genetically high-risk children were followed from birth until the development of IA and progression to T1D. Exposures included energy-adjusted iron intake in the first 3 years of life and a genetic risk score (GRS) for increased circulating iron.

RESULTS

We found a U-shaped association between iron intake and risk of GAD antibody as the first autoantibody. In children with GRS ≥2 iron risk alleles, high iron intake was associated with an increased risk of IA, with insulin as first autoantibody (adjusted hazard ratio 1.71 [95% CI 1.14; 2.58]) compared with moderate iron intake.

CONCLUSIONS

Iron intake may alter the risk of IA in children with high-risk HLA haplogenotypes.

A beta cell subset with enhanced insulin secretion and glucose metabolism is reduced in type 2 diabetes

The pancreatic islets are composed of discrete hormone-producing cells that orchestrate systemic glucose homeostasis. Here we identify subsets of beta cells using a single-cell transcriptomic approach. One subset of beta cells marked by high CD63 expression is enriched for the expression of mitochondrial metabolism genes and exhibits higher mitochondrial respiration compared with CD63lo beta cells. Human and murine pseudo-islets derived from CD63hi beta cells demonstrate enhanced glucose-stimulated insulin secretion compared with pseudo-islets from CD63lo beta cells. We show that CD63hi beta cells are diminished in mouse models of and in humans with type 2 diabetes. Finally, transplantation of pseudo-islets generated from CD63hi but not CD63lo beta cells into diabetic mice restores glucose homeostasis. These findings suggest that loss of a specific subset of beta cells may lead to diabetes. Strategies to reconstitute or maintain CD63hi beta cells may represent a potential anti-diabetic therapy.

Iron metabolism and ferroptosis in type 2 diabetes mellitus and complications: mechanisms and therapeutic opportunities

The maintenance of iron homeostasis is essential for proper endocrine function. A growing body of evidence suggests that iron imbalance is a key factor in the development of several endocrine diseases. Nowadays, ferroptosis, an iron-dependent form of regulated cell death, has become increasingly recognized as an important process to mediate the pathogenesis and progression of type 2 diabetes mellitus (T2DM). It has been shown that ferroptosis in pancreas β cells leads to decreased insulin secretion; and ferroptosis in the liver, fat, and muscle induces insulin resistance. Understanding the mechanisms concerning the regulation of iron metabolism and ferroptosis in T2DM may lead to improved disease management. In this review, we summarized the connection between the metabolic pathways and molecular mechanisms of iron metabolism and ferroptosis in T2DM. Additionally, we discuss the potential targets and pathways concerning ferroptosis in treating T2DM and analysis the current limitations and future directions concerning these novel T2DM treatment targets.

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.

Impact of iron supplementation on gestational diabetes mellitus: A literature review

Gestational diabetes mellitus (GDM) is a common complication of pregnancy, affecting 14% of pregnancies worldwide, and the prevention of pathological hyperglycaemia during pregnancy is meaningful for global public health. The role of iron supplementation in the progression of GDM has been of significant interest in recent years. Iron is a micronutrient that is vital during pregnancy; however, given the toxic properties of excess iron, it is probable that prophylactic iron supplementation will increase the risk of adverse pregnancy outcomes, including GDM. It is critical to clarify the effect of iron supplementation on the risk of GDM. Therefore, in this review, we comprehensively assess the role of iron in pregnancy. This review aimed to analyse the necessity of iron supplementation and maintenance of iron homeostasis during pregnancy, particularly reviewing the role and function of iron in beta cells and examining the mechanisms of excess iron contributing to the pathogenesis of GDM. Moreover, we aimed to discuss the association of haemoglobin and ferritin with GDM and identify priority areas for research.

The association of iron status, supplement iron in the first-trimester pregnancy with gestational diabetes mellitus: A nested case-control study

AIMS

The objective of this study was to examine whether the level of iron and iron supplements in the first-trimester pregnancy is associated with gestational diabetes mellitus (GDM).

METHODS

This was a nested case-control study using data from an established cohort in the Hunan Provincial Maternal and Child Health Hospital (HPMCHH) in South China. A total of 119 patients with GDM and 238 controls were enrolled in the study. Iron status indicators were tested in early pregnancy. Information on iron supplements use was collected by questionnaires. Binary logistic regression was used to obtain odds ratio (OR). The relative excess risk of interaction (RERI) was applied to evaluate the interaction.

RESULTS

We observed that pregnant women with normal ferritin levels (≥30 ng/ml) and iron supplements were associated with a 3.701-fold increased risk of GDM (OR: 3.701, 95% CI: 1.689-8.112) compared with the ferritin <30 ng/ml and without iron supplements group. Similarly, pregnant women with normal serum iron (SI) levels (≥9 μmol/L) and iron supplements were associated with a 5.447-fold increased risk of GDM (OR: 5.447, 95% CI: 2.246-13.209) compared with the SI < 9 μmol/L and without iron supplement group. We found an additive interaction between ferritin and iron supplements on the presence of GDM (RERI: 1.164, 95%CI: 0.333-1.994) and SI and iron supplements on the risk of GDM (RERI: 6.375, 95%CI: 4.494-8.256).

CONCLUSION

Pregnant women with normal ferritin or SI levels and iron supplements could significantly increase the risks for GDM.

The Effect of Dietary Protein Intake on the Risk of Gestational Diabetes

Background. The results of epidemiological studies on the association between dietary protein intake and gestational diabetes mellitus (GDM) are controversial. Thus, this systematic review and meta-analysis of cohort studies were established to attain comprehensive findings regarding the association between dietary protein and the risk of GDM. Methods. Bibliographic databases including PubMed, Scopus, Web of Science, and Google Scholar were searched to discover papers related to dietary protein and the risk of GDM. The summary relative risks with 95% confidence intervals (CIs) were estimated through a random effect model for the analysis of the highest versus the lowest categories of dietary proteins. Results. A significantly increased risk of GDM among women who consumed the highest amount of animal protein was observed (summarized risk estimate: 1.52; 95% CI: 1.07, 2.17; I2 = 50.8%). No significant associations were identified regarding vegetable protein (summarized risk estimate:0.99, 95% CI: 0.80 to 1.23, I2 = 63.8%) and total protein (summarized risk estimate: 1.12; 95% CI: 0.88, 1.41; I2 = 35.4%). Conclusion. This review revealed that total protein intake had no relationship with the risk of GDM, while animal protein increases this risk. Further larger prospective cohort studies are required to confirm our results.

Altered Metal Homeostasis Associates with Inflammation, Oxidative Stress, Impaired Glucose Metabolism, and Dyslipidemia in the Crosstalk between Childhood Obesity and Insulin Resistance

Metals are redox-active substances that participate in central biological processes and may be involved in a multitude of pathogenic events. However, considering the inconsistencies reported in the literature, further research is crucial to disentangle the role of metal homeostasis in childhood obesity and comorbidities using well-characterized cohorts and state-of-the-art analytical methods. To this end, we studied an observational population comprising children with obesity and insulin resistance, children with obesity without insulin resistance, and healthy control children. A multi-elemental approach based on the size-fractionation of metal species was applied to quantify the total content of various essential and toxic elements in plasma and erythrocyte samples, and to simultaneously investigate the metal fractions conforming the metalloproteome and the labile metal pool. The most important disturbances in childhood obesity were found to be related to elevated circulating copper levels, decreased content of plasmatic proteins containing chromium, cobalt, iron, manganese, molybdenum, selenium, and zinc, as well as the sequestration of copper, iron, and selenium within erythrocytes. Interestingly, these metal disturbances were normally exacerbated among children with concomitant insulin resistance, and in turn were associated to other characteristic pathogenic events, such as inflammation, oxidative stress, abnormal glucose metabolism, and dyslipidemia. Therefore, this study represents one-step further towards a better understanding of the involvement of metals in the crosstalk between childhood obesity and insulin resistance.

Iron Supplementation in Pregnancy and Risk of Gestational Diabetes: A Narrative Review

Pregnant women frequently supplement their diets with iron to treat any cryptic anemia, on the assumption that if anemia is not present, there will be no negative consequences. However, in women who are already iron-replete, it has been suggested that this can lead to iron overload and an increased risk of certain pregnancy complications. One such complication is gestational diabetes. Fourteen clinical trials, case-control or cohort studies (found using Pubmed/Scopus/Web of Science) have investigated links between iron supplementation in pregnancy and risk of gestational diabetes, several of them finding significant associations with increased risk. Potential mechanisms include increased oxidative stress leading to insulin resistance and inadequate compensatory insulin secretion. Current evidence suggests that dietary supplementation with iron in pregnancy may increase a pregnant woman's chance of developing gestational diabetes, although available evidence is somewhat contradictory, and the magnitude of any increased risk appears relatively small. Meta-analyses have suggested the presence of significant heterogeneity in results between studies, urging a degree of caution in interpreting these results. It is currently suggested that advice to pregnant women about whether to supplement their diets with iron or not should consider both their current iron status and their other established risk factors for gestational diabetes.

Protective effect of traditional Chinese medicine on non-alcoholic fatty liver disease and liver cancer by targeting ferroptosis

Non-alcoholic fatty liver disease (NAFLD) is a chronic liver disease with high incidence and is closely related to metabolic syndrome. If not controlled, it may eventually become hepatocellular carcinoma (HCC). Ferroptosis, a non-apoptotic form of programmed cell death (PCD), is closely related to NAFLD and HCC, and the mechanisms of action involved are more complex. Some studies have demonstrated that many drugs inhibit ferroptosis and protect liver steatosis or carcinogenesis. The role of Traditional Chinese Medicine (TCM), especially herbs or herbal extracts, has received increasing attention. However, there are relatively few review articles on the regulation of NAFLD by TCM through ferroptosis pathway. Here, we summarize the TCM intervention mechanism and application affecting NAFLD/NAFLD-HCC via regulation of ferroptosis. This article focuses on the relationship between ferroptosis and NAFLD or NAFLD-HCC and the protective effect of TCM on both by targeting ferroptosis. It not only summarizes the mechanism of early prevention and treatment of NAFLD, but also provides reference ideas for the development of TCM for the treatment of metabolic diseases and liver diseases.

Impaired pancreatic beta-cell function after a single dose of oral iron: a before-and-after (pre-post) study

INTRODUCTION

Although in vitro and animal studies have shown that iron loading in pancreatic beta-cells impaired insulin secretion, no human studies have documented the acute effects of oral iron on beta-cell insulin secretory capacity. In this study, we determined beta-cell insulin secretory capacity at baseline and after a single oral dose of iron (ferrous sulphate, 120 mg elemental iron) in healthy male individuals.

METHODS

Fifteen healthy male volunteers underwent an oral glucose tolerance test (OGTT) to document baseline glucose tolerance and insulin secretion kinetics (baseline OGTT). One week later, the same subjects underwent a second OGTT, two hours after an oral dose of ferrous sulfate (120 mg of elemental iron) (post-iron OGTT). Changes in disposition index, insulin secretion kinetics, glucose tolerance, insulin resistance, insulin clearance, and iron-related parameters in serum were determined.

RESULTS

Compared to baseline OGTT, the areas under the curve (AUC) for serum iron and transferrin saturation increased by 125% and 118% respectively, in the post-iron OGTT. The disposition index decreased by 20% (p=0.009) and the AUC for glucose concentrations increased by 5.7% (p<0.001) during the post-iron OGTT. The insulin secretion rate was marginally lower during the first hour (-3.5%, p=0.63), but became significantly higher during the second hour (22%, p=0.005) of the post-iron OGTT. Insulin resistance and insulin clearance rate were not affected by iron intake.

CONCLUSION

The decrease in disposition index and glucose tolerance observed after the oral dose of iron points to an acute iron-induced impairment in pancreatic beta-cell insulin secretory capacity. This article is protected by copyright. All rights reserved.

Ferroptosis and metabolic dysfunction-associated fatty liver disease: Is there a link?

Non-alcoholic fatty liver disease (NAFLD), recently re-defined and re-classified as metabolic dysfunction-associated fatty liver disease (MAFLD), has become increasingly prevalent and emerged as a public health problem worldwide. To date, the precise pathogenic mechanisms underpinning MAFLD are not entirely understood, and there is no effective pharmacological therapy for NAFLD/MAFLD. As a newly discovered form of iron-dependent programmed cell death, ferroptosis can be involved in the development and progression of various chronic diseases, but the pathogenic connections and mechanisms that link MAFLD and ferroptosis have not been fully elucidated. The main characteristics of ferroptosis are the accumulation of lipid peroxides and reactive oxygen species. In this brief narrative review, the mechanisms of ferroptosis and its putative pathogenic role in MAFLD are discussed to highlight potential new research directions and ideas for the prevention and treatment of MAFLD.

Regenerating islet-derived protein 3 gamma (Reg3g) ameliorates tacrolimus-induced pancreatic β-cell dysfunction in mice by restoring mitochondrial function

BACKGROUND AND PURPOSE

Tacrolimus a first-line medication used after transplantation can induce β-cell dysfunction, causing new-onset diabetes mellitus (NODM). Regenerating islet-derived protein 3 gamma (Reg3g), a member of the pancreatic regenerative gene family, has been reported to improve type 1 diabetes by promoting β-cell regeneration. We aim to investigate the role of Reg3g in reversing tacrolimus-induced β-cell dysfunction and NODM in mice.

EXPERIMENTAL APPROACH

Circulating REG3A (the human homologue of mouse Reg3g) in heart transplantation patients treated with tacrolimus was detected. The glucose-stimulated insulin secretion and mitochondrial functions, including mitochondria membrane potential (MMP), mitochondria calcium, ATP production, oxygen consumption rate and mitochondrial morphology were investigated in β-cells. Additionally, effects of Reg3g on tacrolimus-induced NODM in mice were analysed.

KEY RESULTS

Circulating REG3A level in heart transplantation patients with NODM significantly decreased compared with those without diabetes. Tacrolimus down-regulated Reg3g via inhibiting STAT3-mediated transcription activation. Moreover, Reg3g restored glucose-stimulated insulin secretion suppressed by tacrolimus in β-cells by improving mitochondrial functions, including increased MMP, mitochondria calcium uptake, ATP production, oxygen consumption rate and contributing to an intact mitochondrial morphology. Mechanistically, Reg3g increased accumulation of pSTAT3(Ser727) in mitochondria by activating ERK1/2-STAT3 signalling pathway, leading to restoration of tacrolimus-induced mitochondrial impairment. Reg3g overexpression also effectively mitigated tacrolimus-induced NODM in mice.

CONCLUSION AND IMPLICATIONS

Reg3g can significantly ameliorate tacrolimus-induced β-cell dysfunction by restoring mitochondrial function in a pSTAT3(Ser727)-dependent manner. Our observations identify a novel Reg3g-mediated mechanism that is involved in tacrolimus-induced NODM and establish the novel role of Reg3g in reversing tacrolimus-induced β-cell dysfunction.

Association between hepatic iron overload assessed by magnetic resonance imaging and glucose intolerance states in the general population

BACKGROUND AND AIM

While there is evidence that iron overload disorders are associated with type 2 diabetes, the relationship between hepatic iron overload and prediabetes remains unclear. We aimed to investigate the association between hepatic iron overload, as assessed by magnetic resonance imaging (MRI), and different glucose intolerance states in the population-based Study.

METHODS AND RESULTS

We included data from 1622 individuals with MRI data, who did not have known type 2 diabetes (T2DM). Using an oral glucose tolerance testing, participants were classified as having isolated impaired fasting glucose (i-IFG), isolated impaired glucose tolerance (i-IGT), combined IFG and IGT (IFG + IGT) or previously unknown T2DM. Hepatic iron and fat contents were assessed through quantitative MRI. We undertook linear and multinomial logistic regression models adjusted for potential confounders and MRI-assessed hepatic fat content to examine the association of hepatic iron overload with different glucose intolerance states or continuous markers of glucose metabolism. MRI-assessed hepatic iron overload was positively associated only with both 2-h plasma glucose (β = 0.32; 95%CI 0.04-0.60) and the combined IFG + IGT category (relative risk ratio = 1.87; 95%CI 1.15-3.06). No significant associations were found between hepatic iron overload and other glucose intolerance states or biomarkers of glucose metabolism, independently of potential confounders.

CONCLUSIONS

MRI-assessed hepatic iron overload was associated with higher 2-h glucose concentrations and the combined IFG + IGT category, but not with other glucose intolerance states. Our findings suggest a weak adverse impact of hepatic iron overload on glucose metabolism, but further studies are needed to confirm these findings.

An anti-diabetic drug targets NEET (CISD) proteins through destabilization of their [2Fe-2S] clusters

Elevated levels of mitochondrial iron and reactive oxygen species (ROS) accompany the progression of diabetes, negatively impacting insulin production and secretion from pancreatic cells. In search for a tool to reduce mitochondrial iron and ROS levels, we arrived at a molecule that destabilizes the [2Fe-2S] clusters of NEET proteins (M1). Treatment of db/db diabetic mice with M1 improved hyperglycemia, without the weight gain observed with alternative treatments such as rosiglitazone. The molecular interactions of M1 with the NEET proteins mNT and NAF-1 were determined by X-crystallography. The possibility of controlling diabetes by molecules that destabilize the [2Fe-2S] clusters of NEET proteins, thereby reducing iron-mediated oxidative stress, opens a new route for managing metabolic aberration such as in diabetes.

Nociceptor-derived Reg3γ prevents endotoxic death by targeting kynurenine pathway in microglia

Nociceptors can fine-tune local or systemic immunity, but the mechanisms of nociceptive modulation in endotoxic death remain largely unknown. Here, we identified C-type lectin Reg3γ as a nociceptor-enriched hormone that protects the host from endotoxic death. During endotoxemia, nociceptor-derived Reg3γ penetrates the brain and suppresses the expression of microglial indoleamine dioxygenase 1, a critical enzyme of the kynurenine pathway, via the Extl3-Bcl10 axis. Endotoxin-administered nociceptor-null mice and nociceptor-specific Reg3γ-deficient mice exhibit a high mortality rate accompanied by decreased brain HK1 phosphorylation and ATP production despite normal peripheral inflammation. Such metabolic arrest is only observed in the brain, and aberrant production of brain quinolinic acid, a neurotoxic metabolite of the kynurenine pathway, causes HK1 suppression. Strikingly, the central administration of Reg3γ protects mice from endotoxic death by enhancing brain ATP production. By identifying nociceptor-derived Reg3γ as a microglia-targeted hormone, this study provides insights into the understanding of tolerance to endotoxic death.

Iron Overload and the Risk of Diabetes in the General Population: Results of the Chinese Health and Nutrition Survey Cohort Study

BACKGROUND

Recent studies have found that there are significant associations between body iron status and the development of diabetes. In the present study, we aimed to analyze the association among iron overload (IO), insulin resistance (IR), and diabetes in Chinese adults, and to explore the sex difference.

METHODS

Men and women (age >19 years) who participated in the Chinese Health and Nutrition Survey and did not have diabetes at baseline were followed between 2009 and 2015 (n=5,779). Over a mean of 6 years, 75 participants were diagnosed with incident diabetes. Logistic regression was used to assess the risk factors associated with IO. Cox proportional hazard regression was used to estimate the risk of incident diabetes and to determine whether the risk differed among subgroups. Causal mediation analysis (CMA) was used to explore the mechanism linking IO and diabetes.

RESULTS

According to sex-stratified multivariable-adjusted Cox proportional hazards regression, IO increased the risk of incident diabetes. Women with IO had a higher risk of diabetes than men. Subgroup analysis with respect to age showed that the association between IO and diabetes was stronger in older women and younger men (P<0.001). CMA showed that liver injury (alanine transaminase) and lipid metabolism abnormalities (triglyceride, apolipoprotein B) contributed to the association between IO and diabetes.

CONCLUSION

IO is associated with diabetes and this association is sex-specific. IO may indirectly induce IR via liver injury and lipid metabolism abnormalities, resulting in diabetes.

Anemia in Chronic Kidney Disease Patients: An Update

Chronic kidney disease (CKD) is one of the most common disabling diseases globally. The main etiopathology of CKD is attributed to progressive renal fibrosis secondary to recurrent renal insults. Anemia is a known complication in CKD patients, associated with higher hospitalization rates and increased mortality risk. CKD-associated anemia (CKD-AA) is either due to true iron deficiency and/or functional iron deficiency anemia. There is new emerging evidence about the effects of erythropoiesis stimulating agents in the treatment of CKD-AA and their role in reversing and preventing kidney fibrosis in the early stages of CKD. This effect potentially provides new scopes in the prevention and treatment of CKD-AA and in decreasing the progression of CKD and the associated long-term complications. Epidemiology, pathophysiology, and treatments of CKD-AA will be discussed.

The Role of Estrogen Signaling in Cellular Iron Metabolism in Pancreatic β Cells

ABSTRACT

Several lines of evidence suggest that estrogen (17-β estradiol; E2) protects against diabetes mellitus and plays important roles in pancreatic β-cell survival and function. Mounting clinical and experimental evidence also suggest that E2 modulates cellular iron metabolism by regulating the expression of several iron regulatory genes, including hepcidin (HAMP), hypoxia-inducible factor 1-α, ferroportin (SLC40A1), and lipocalin (LCN2). However, whether E2 regulates cellular iron metabolism in pancreatic β cells and whether the antidiabetic effects of E2 can be, at least partially, attributed to its role in iron metabolism is not known. In this context, pancreatic β cells express considerable levels of conventional E2 receptors (ERs; mainly ER-α) and nonconventional G protein-coupled estrogen receptors and hence responsive to E2 signals. Moreover, pancreatic islet cells require significant amounts of iron for proper functioning, replication and survival and, hence, well equipped to manage cellular iron metabolism (acquisition, utilization, storage, and release). In this review, we examine the link between E2 and cellular iron metabolism in pancreatic β cells and discuss the bearing of such a link on β-cell survival and function.

Double-edge sword roles of iron in driving energy production versus instigating ferroptosis

Iron is vital for many physiological functions, including energy production, and dysregulated iron homeostasis underlies a number of pathologies. Ferroptosis is a recently recognized form of regulated cell death that is characterized by iron dependency and lipid peroxidation, and this process has been reported to be involved in multiple diseases. The mechanisms underlying ferroptosis are complex, and involve both well-described pathways (including the iron-induced Fenton reaction, impaired antioxidant capacity, and mitochondrial dysfunction) and novel interactions linked to cellular energy production. In this review, we examine the contribution of iron to diverse metabolic activities and their relationship to ferroptosis. There is an emphasis on the role of iron in driving energy production and its link to ferroptosis under both physiological and pathological conditions. In conclusion, excess reactive oxygen species production driven by disordered iron metabolism, which induces Fenton reaction and/or impairs mitochondrial function and energy metabolism, is a key inducer of ferroptosis.

Heme Oxygenase-1 (HMOX-1) and inhibitor of differentiation proteins (ID1, ID3) are key response mechanisms against iron-overload in pancreatic β-cells

Iron overload promotes the generation of reactive oxygen species (ROS). Pancreatic β-cells can counter oxidative stress through multiple anti-oxidant responses. Herein, RNA-sequencing was used to describe the expression profile of iron regulatory genes in human islets with or without diabetes. Functional experiments including siRNA silencing, qPCR, western blotting, cell viability, ELISA and RNA-sequencing were performed as means of identifying the genetic signature of the protective response following iron overload-induced stress in human islets and INS-1. FTH1 and FTL genes were highly expressed in human islets and INS-1 cells, while hepcidin (HAMP) was low. FXN, DMT1 and FTHL1 genes were differentially expressed in diabetic islets compared to control. Silencing of Hamp in INS-1 cells impaired insulin secretion and influenced the expression of β-cell key genes. RNA-sequencing analysis in iron overloaded INS-1 cells identified Id1 and Id3 as the top down-regulated genes, while Hmox1 was the top upregulated. Expression of ID1, ID3 and HMOX1 was validated at the protein level in INS-1 cells and human islets. Differentially expressed genes (DEGs) were enriched for TGF-β, regulating stem cells, ferroptosis, and HIF-1 signaling. Hmox1-silenced cells treated with FAC elevated the expression of Id1 and Id3 expression than untreated cells. Our findings suggest that HMOX1, ID1 and ID3 define the response mechanism against iron-overload-induced stress in β-cells.

Hemochromatosis, Iron Overload-Related Diseases, and Pancreatic Cancer Risk in the Surveillance, Epidemiology, and End Results (SEER)-Medicare

BACKGROUND

Experimental studies suggest that iron overload might increase pancreatic cancer risk. We evaluated whether prediagnostic hemochromatosis and iron-overload diseases, including sideroblastic and congenital dyserythropoietic anemias, and non-alcoholic-related chronic liver disease (NACLD) were associated with pancreatic cancer risk in older adults.

METHODS

We conducted a population-based, case-control study within the U.S. Surveillance, Epidemiology, and End Results Program (SEER)-Medicare linked data. Incident primary pancreatic cancer cases were adults > 66 years. Controls were alive at the time cases were diagnosed and matched to cases (4:1 ratio) by age, sex, and calendar year. Hemochromatosis, iron-overload anemias, and NACLD were reported 12 or more months before pancreatic cancer diagnosis or control selection using Medicare claims data. Adjusted unconditional logistic regression models were used to calculate ORs and 95% confidence intervals (CI) between hemochromatosis, sideroblastic and congenital dyserythropoietic anemias, NACLD, and pancreatic cancer.

RESULTS

Between 1992 and 2015, 80,074 pancreatic cancer cases and 320,296 controls were identified. Overall, we did not observe statistically significant associations between hemochromatosis, sideroblastic anemia, or congenital dyserythropoietic anemia and pancreatic cancer; however, sideroblastic anemia was associated with later primary pancreatic cancer (OR, 1.30; 95% CI, 1.03-1.64). NACLD was associated with first (OR, 1.10; 95% CI, 1.01-1.19), later (OR, 1.17; 95% CI, 1.02-1.35), and all (OR, 1.12; 95% CI, 1.04-1.20) pancreatic cancer.

CONCLUSIONS

Overall hemochromatosis and iron-overload anemias were not associated with pancreatic cancer, whereas NACLD was associated with increased risk in this large study of older adults.

IMPACT

These results partly support the hypothesis that iron-overload diseases increase pancreatic cancer risk.

Iron Metabolism in Pancreatic Beta-Cell Function and Dysfunction

Iron is an essential element involved in a variety of physiological functions. In the pancreatic beta-cells, being part of Fe-S cluster proteins, it is necessary for the correct insulin synthesis and processing. In the mitochondria, as a component of the respiratory chain, it allows the production of ATP and reactive oxygen species (ROS) that trigger beta-cell depolarization and potentiate the calcium-dependent insulin release. Iron cellular content must be finely tuned to ensure the normal supply but also to prevent overloading. Indeed, due to the high reactivity with oxygen and the formation of free radicals, iron excess may cause oxidative damage of cells that are extremely vulnerable to this condition because the normal elevated ROS production and the paucity in antioxidant enzyme activities. The aim of the present review is to provide insights into the mechanisms responsible for iron homeostasis in beta-cells, describing how alteration of these processes has been related to beta-cell damage and failure. Defects in iron-storing or -chaperoning proteins have been detected in diabetic conditions; therefore, the control of iron metabolism in these cells deserves further investigation as a promising target for the development of new disease treatments.

Hepcidin-regulating iron metabolism genes and pancreatic ductal adenocarcinoma: a pathway analysis of genome-wide association studies

BACKGROUND

Epidemiological studies have suggested positive associations for iron and red meat intake with risk of pancreatic ductal adenocarcinoma (PDAC). Inherited pathogenic variants in genes involved in the hepcidin-regulating iron metabolism pathway are known to cause iron overload and hemochromatosis.

OBJECTIVES

The objective of this study was to determine whether common genetic variation in the hepcidin-regulating iron metabolism pathway is associated with PDAC.

METHODS

We conducted a pathway analysis of the hepcidin-regulating genes using single nucleotide polymorphism (SNP) summary statistics generated from 4 genome-wide association studies in 2 large consortium studies using the summary data-based adaptive rank truncated product method. Our population consisted of 9253 PDAC cases and 12,525 controls of European descent. Our analysis included 11 hepcidin-regulating genes [bone morphogenetic protein 2 (BMP2), bone morphogenetic protein 6 (BMP6), ferritin heavy chain 1 (FTH1), ferritin light chain (FTL), hepcidin (HAMP), homeostatic iron regulator (HFE), hemojuvelin (HJV), nuclear factor erythroid 2-related factor 2 (NRF2), ferroportin 1 (SLC40A1), transferrin receptor 1 (TFR1), and transferrin receptor 2 (TFR2)] and their surrounding genomic regions (±20 kb) for a total of 412 SNPs.

RESULTS

The hepcidin-regulating gene pathway was significantly associated with PDAC (P = 0.002), with the HJV, TFR2, TFR1, BMP6, and HAMP genes contributing the most to the association.

CONCLUSIONS

Our results support that genetic susceptibility related to the hepcidin-regulating gene pathway is associated with PDAC risk and suggest a potential role of iron metabolism in pancreatic carcinogenesis. Further studies are needed to evaluate effect modification by intake of iron-rich foods on this association.

Iron intake and multiple health outcomes: Umbrella review

Iron is an essential trace element, while excess iron can lead to different levels of physical abnormalities or diseases. This umbrella review aimed to conduct a systematic evaluation of the possible relationships between iron intake and various health outcomes. We retrieved PubMed, Embase, Web of Science, Scopus, and the Cochrane Database of Systematic Reviews from inception through May 2021. A total of 34 meta-analyses with 46 unique health outcomes were identified. Heme iron intake was positively associated with nine outcomes, including colorectal cancer, type 2 diabetes mellitus, and cardiovascular disease mortality, while dietary total iron intake could decrease the risk of colorectal adenoma, esophageal cancer, coronary heart disease, and depression. Iron supplementation was a protective factor against eight outcomes. However, it was associated with decreased length and weight gain. The quality of evidence for most outcomes was "low" or "very low" with the remaining eleven as "high" or "moderate". All outcomes were categorized as class III, IV, or NS based on evidence classification. Although high iron intake has been identified to be significantly associated with a range of outcomes, firm universal conclusions about its beneficial or negative effects cannot be drawn given the low quality of evidence for most outcomes.

Divalent Metal Transporter 1 Knock-Down Modulates IL-1β Mediated Pancreatic Beta-Cell Pro-Apoptotic Signaling Pathways through the Autophagic Machinery

Pro-inflammatory cytokines promote cellular iron-import through enhanced divalent metal transporter-1 (DMT1) expression in pancreatic β-cells, consequently cell death. Inhibition of β-cell iron-import by DMT1 silencing protects against apoptosis in animal models of diabetes. However, how alterations of signaling networks contribute to the protective action of DMT1 knock-down is unknown. Here, we performed phosphoproteomics using our sequential enrichment strategy of mRNA, protein, and phosphopeptides, which enabled us to explore the concurrent molecular events in the same set of wildtype and DMT1-silenced β-cells during IL-1β exposure. Our findings reveal new phosphosites in the IL-1β-induced proteins that are clearly reverted by DMT1 silencing towards their steady-state levels. We validated the levels of five novel phosphosites of the potential protective proteins using parallel reaction monitoring. We also confirmed the inactivation of autophagic flux that may be relevant for cell survival induced by DMT1 silencing during IL-1β exposure. Additionally, the potential protective proteins induced by DMT1 silencing were related to insulin secretion that may lead to improving β-cell functions upon exposure to IL-1β. This global profiling has shed light on the signal transduction pathways driving the protection against inflammation-induced cell death in β-cells after DMT1 silencing.

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.

Vitamin D Rescues Pancreatic β Cell Dysfunction due to Iron Overload via Elevation of the Vitamin D Receptor and Maintenance of Ca2+ Homeostasis

SCOPE

Accumulating evidence indicates that micronutrients are related to metabolic diseases. However, comparatively less attention has been devoted to their influence on each other during the development of metabolic diseases. To investigate the underlying mechanisms, the effects of iron and vitamin D on pancreatic β cell functions are examined.

METHODS AND RESULTS

Iron overload is induced in INS-1 rat insulinoma pancreatic β cells and it is found that iron overload dramatically reduce expression of the vitamin D receptor (VDR). Iron overload-induced β cell dysfunction is rescued by 1,25-dihydroxyvitamin D3 (1,25(OH)2 D3 ) cotreatment via restoration of VDR level and the consequent maintenance of Ca2+ homeostasis. Iron accumulation is also observed in the islets of 22-month-old C57BL/6 mice fed with a chow diet (1000 IU vitamin D3 per kg). In contrast, islet iron accumulation and hyperinsulinemia are ameliorated in mice fed with a vitamin D3 -supplemented diet (20 000 IU kg-1 ).

CONCLUSION

The authors show that functional failure of β cells due to iron accumulation is rescued by 1,25(OH)2 D3 , and iron overload significantly reduces VDR levels in β cells. These results suggest that iron and vitamin D inversely influence pancreatic β cell function.

Prepregnancy hemoglobin levels and gestational diabetes mellitus in pregnancy

AIM

To identify the influence of prepregnancy hemoglobin levels on gestational diabetes mellitus.

MATERIALS AND METHODS

Korean women who had given birth between January 1st, 2006 and December 31st, 2015 and who had undergone a biannual national health screening examination within 6 months prior to pregnancy were enrolled. Subjects were divided into three groups according to their hemoglobin levels. Multivariate logistic regression analysis was used to estimate the adjusted odds ratio and 95% confidence interval for GDM.

RESULTS

Of the 366,122 participants, GDM developed in 14,799 (4%) women. More specifically, GDM developed in 3.6% of women with prepregnancy anemia (hemoglobin < 11 g/dL), 3.57% with normal hemoglobin levels, and 4.47% with hemoglobin levels higher than 13 g/dL. We did not find any association between prepregnancy anemia and the risk of developing GDM (OR 1.002 [95% CI 0.90-1.11]). After adjusting for potential confounding factors (adjusted odds ratio 1.41; 95% CI 1.29-1.54), high hemoglobin levels were associated with insulin requiring GDM.

CONCLUSIONS

Our study identified an association between high prepregnancy hemoglobin levels and GDM risk.

Use of 2-dimensional cell monolayers and 3-dimensional microvascular networks on microfluidic devices shows that iron increases transendothelial adiponectin flux via inducing ROS production

BACKGROUND

Iron excess is a risk factor for cardiovascular diseases and it is important to understand the effect of iron on vascular permeability, particularly for the transport of large metabolic hormones such as adiponectin.

METHODS

We used 2-dimensional monolayers of cultured human dermal microvascular endothelial cells (HDMEC) and human umbilical vein endothelial cells (HUVEC) as well as 3-dimensional microvascular networks to measure transendothelial flux.

RESULTS

Iron supplementation reduced transendothelial electric resistance (TEER). Flux analysis indicated that under control conditions permeability of 70 kDa dextran and oligomeric forms of adiponectin were restricted in comparison with a 3 kDa dextran, however upon iron treatment permeability of the larger molecules was increased. The increased permeability and size-dependent trans-endothelial movement in response to iron was also observed in 3-dimensional microvascular networks. Mechanistically, the alteration in barrier functionality was associated with increased oxidative stress in response to iron since alterations in TEER and permeability were rescued when reactive oxygen species production was attenuated by pre-treatment with the antioxidant N-acetyl cysteine.].

CONCLUSIONS

Iron supplementation induced ROS production resulting in increased transendothelial permeability.

GENERAL SIGNIFICANCE

Altogether, this suggests that the oxidative stress associated with iron excess could play an important role in the regulation of endothelial functionality, controlling hormone action in peripheral tissues by regulating the first rate-limiting step controlling hormone access to target tissues.

Dalteparin as a Novel Therapeutic Agent to Prevent Diabetic Encephalopathy by Targeting Oxidative Stress and Inflammation

Introduction:

Hepcidin is the main modulator of systemic iron metabolism, and its role in the brain has been clarified recently. Studies have shown that hepcidin plays an important role in neuronal iron load and inflammation. This issue is of significance because neuronal iron load and inflammation are pathophysiological processes that are highly linked to neurodegeneration. Moreover, the activity of hepcidin has recently been manipulated to recover the neuronal impairment caused by brain inflammation in animal models.

Methods:

Streptozotocin (STZ) was used to induce type 1 diabetes. Male Wistar rats (n = 40) with a weight range of 200–250 g were divided into control, diabetic, diabetic + insulin, and diabetic + dalteparin groups. Dalteparin (100 mg/kg IP) and insulin (100 mg/kg SC) were administered for 8 weeks. At the end of the experiment, Y-maze and passive avoidance tasks were carried out. The animals were perfused randomly and their hippocampal tissue was isolated for the analysis of markers such as lipid peroxidation like Malondialdehyde (MDA), hepcidin expression, iron, and ferritin. Blood samples were taken for the measurement of serum inflammatory cytokine Interleukin (IL)-6.

Results:

The findings indicated that treatment with dalteparin reduced IL-6, MDA, ferritin, and hepcidin expression in diabetic rats compared to treatment with insulin (P<0.05). Moreover, treatment with dalteparin did not decrease the iron level or prevented its decline.

Conclusion:

Treatment with dalteparin improved the cognitive dysfunctions and symptoms of Alzheimer disease in STZ-induced diabetic rats by appropriately modulating and reducing oxidative stress and neuroinflammation. This may enhance the existing knowledge of therapeutics to reduce cognitive impairment in diabetes and is suggested to be a potential therapeutic agent in diabetes.

The relationship between iron metabolism, stress hormones, and insulin resistance in gestational diabetes mellitus

AIM

To analyze the relationship between iron metabolism index and stress hormones, insulin resistance, and oxidative stress in gestational diabetes mellitus (GDM).

METHODS

From January to November 2019, 75 patients with GDM were selected as GDM group, according to age of 1:1; 75 normal pregnant women were selected as Control group. Blood glucose, insulin, stress hormones such as cortisol, norepinephrine (NE), and epinephrine (E), and iron metabolism index such as serum iron, serum ferritin (SF), and transferrin saturation (TS) were measured. Insulin resistance was evaluated by homeostasis model insulin resistance index (HOMA-IR). Multiple linear regression was used to analyze the relationship between iron metabolism index and stress hormones, insulin resistance, and oxidative stress.

RESULTS

The levels of NE, E, serum iron, SF, and TS saturation in the GDM group were higher than Control group (t = 3.82, 2.75, 3.14, 6.12, and 3.90, P < 0.05, <0.05, <0.05, <0.01, <0.01); HOMA-IR was higher in the GDM group (t = 4.92, P < 0.01); malondialdehyde (MDA) was higher, while superoxide dismutase (SOD) was lower than Control group (t = 5.25, 4.98, both P < 0.01). Epinephrine, norepinephrine, cortisol, and serum ferritin were positively correlated (r = 0.21, 0.17, and 0.21); epinephrine, cortisol, and transferrin were positively correlated (r = 0.12, 0.31). There was a positive correlation between HOMA-IR and SF and TS (r = 0.34, 0.34). MDA was positively correlated with SF and TS (r = 0.24, 0.29); SOD was negatively related to SF and TS (r = -0.12, -0.17).

CONCLUSIONS

Iron metabolism index is related to insulin resistance in GDM women. The change in iron metabolism may be involved in the pathogenesis of gestational diabetes caused by stress- adaptive disorder.

Polyphenols and AGEs/RAGE axis. Trends and challenges

The formation of advanced glycation end-products (AGEs) is a key pathophysiological event linked not only to the onset and progression of diabetic complications, but also to neurodegeneration, cardiovascular diseases, cancer, and others important human diseases. AGEs contributions to pathophysiology are mainly through the formation of cross-links and by engaging the receptor for advanced glycation end-products (RAGE). Polyphenols are secondary metabolites found largely in fruits, vegetables, cereals, and beverages, and during many years, important efforts have been made to elucidate their beneficial effects on human health, mainly ascribed to their antioxidant activities. In the present review, we highlighted the beneficial actions of polyphenols aimed to diminish the harmful consequences of advanced glycation, mainly by the inhibition of ROS formation during glycation, the inhibition of Schiff base, Amadori products, and subsequent dicarbonyls group formation, the activation of the glyoxalase system, as well as by blocking either AGEs-RAGE interaction or cell signaling.

Plasma Phospholipids with Long-Chain Polyunsaturated Fatty Acids and Dihydroceramides at the Crossroads of Iron Stores and Insulin Resistance

SCOPE

Iron plays an important role in the pathogenesis of insulin resistance (IR) and type 2 diabetes. Recent studies suggest a role of specific lipids in the induction of IR, but the potential relationships between iron and lipid metabolites in relation to IR have not been explored. Therefore, the aim of the study is to evaluate the association among iron, IR, and the lipidome.

METHODS AND RESULTS

The plasma lipidome, IR, parameters of iron metabolism, and several cytokines and adipokines in 65 overweight/obese participants are measured. Measurements of IR correlate positively with ferritin, a measure of iron storage (r = 0.35, p = 0.005), and negatively with adiponectin (r = -0.30, p = 0.02). The serum ferritin/adiponectin ratio has a stronger association with IR (r = 0.41, p < 0.001). From multivariate analyses adjusted for age, sex, and BMI, several phospholipids containing long chain polyunsaturated fatty acids (PUFA) with 20-22 carbons (phosphatidylcholines, phosphatidylethanolamines, phosphatidylinositols, and a phosphatidylserine), are positively associated with ferritin and the ferritin/adiponectin ratio. Two dihydroceramides (Cer(18:0/22:0), Cer(18:0/24:0)) and several diglycerides and triglycerides, mainly comprised of C14:0, C16:0, C18:0, C18:1, and C18:2, also have positive correlations with ferritin and the ferritin/adiponectin ratio.

CONCLUSIONS

The positive associations between these lipid species and ferritin or the ferritin/adiponectin ratio suggest a potential crosstalk between iron and lipid metabolism in obesity and IR.

Irp2 regulates insulin production through iron-mediated Cdkal1-catalyzed tRNA modification

Regulation of cellular iron homeostasis is crucial as both iron excess and deficiency cause hematological and neurodegenerative diseases. Here we show that mice lacking iron-regulatory protein 2 (Irp2), a regulator of cellular iron homeostasis, develop diabetes. Irp2 post-transcriptionally regulates the iron-uptake protein transferrin receptor 1 (TfR1) and the iron-storage protein ferritin, and dysregulation of these proteins due to Irp2 loss causes functional iron deficiency in β cells. This impairs Fe-S cluster biosynthesis, reducing the function of Cdkal1, an Fe-S cluster enzyme that catalyzes methylthiolation of t⁶A37 in tRNA^Lys_UUU to ms²t⁶A37. As a consequence, lysine codons in proinsulin are misread and proinsulin processing is impaired, reducing insulin content and secretion. Iron normalizes ms²t⁶A37 and proinsulin lysine incorporation, restoring insulin content and secretion in Irp2^-/- β cells. These studies reveal a previously unidentified link between insulin processing and cellular iron deficiency that may have relevance to type 2 diabetes in humans.

Contribution of Oxidative Stress and Impaired Biogenesis of Pancreatic β-Cells to Type 2 Diabetes

Significance: Type 2 diabetes development involves multiple changes in β-cells, related to the oxidative stress and impaired redox signaling, beginning frequently by sustained overfeeding due to the resulting lipotoxicity and glucotoxicity. Uncovering relationships among the dysregulated metabolism, impaired β-cell "well-being," biogenesis, or cross talk with peripheral insulin resistance is required for elucidation of type 2 diabetes etiology. Recent Advances: It has been recognized that the oxidative stress, lipotoxicity, and glucotoxicity cannot be separated from numerous other cell pathology events, such as the attempted compensation of β-cell for the increased insulin demand and dynamics of β-cell biogenesis and its "reversal" at dedifferentiation, that is, from the concomitantly decreasing islet β-cell mass (also due to transdifferentiation) and low-grade islet or systemic inflammation. Critical Issues: At prediabetes, the compensation responses of β-cells, attempting to delay the pathology progression-when exaggerated-set a new state, in which a self-checking redox signaling related to the expression of Ins gene expression is impaired. The resulting altered redox signaling, diminished insulin secretion responses to various secretagogues including glucose, may lead to excretion of cytokines or chemokines by β-cells or excretion of endosomes. They could substantiate putative stress signals to the periphery. Subsequent changes and lasting glucolipotoxicity promote islet inflammatory responses and further pathology spiral. Future Directions: Should bring an understanding of the β-cell self-checking and related redox signaling, including the putative stress signal to periphery. Strategies to cure or prevent type 2 diabetes could be based on the substitution of the "wrong" signal by the "correct" self-checking signal.