Repression of the iron exporter ferroportin may contribute to hepatocyte iron overload in individuals with type 2 diabetes

The role of metal ion metabolism in the pathogenesis of diabetes and associated complications

Diabetes is a growing health concern, accompanied by significant complications like cardiovascular disease, kidney disease, and retinopathy. Metal ions, including iron, zinc, and copper, play a crucial role in maintaining human health through their balance within the body. Disruptions in metal ion balance can intensify diabetic conditions. For instance, iron overload induces oxidative stress, which harms islet β cells and impacts vascular complications of diabetes. Abnormal copper levels heighten insulin resistance, and zinc deficiency has a strong connection with type 1 diabetes. Future in - depth exploration of the association between metal metabolism and diabetes holds the potential to uncover novel treatment avenues, enhancing both the quality of life and health prognosis for patients.

Exploring the therapeutic potential of Chinese herbs on comorbid type 2 diabetes mellitus and Parkinson's disease: A mechanistic study

ETHNOPHARMACOLOGICAL RELEVANCE

Type 2 diabetes mellitus (T2DM) and Parkinson's disease (PD) are chronic conditions that affect the aging population, with increasing prevalence globally. The rising prevalence of comorbidity between these conditions, driven by demographic shifts, severely impacts the quality of life of patients, posing a significant burden on healthcare resources. Chinese herbal medicine has been used to treat T2DM and PD for millennia. Pharmacological studies have demonstrated that medicinal herbs effectively lower blood glucose levels and exert neuroprotective effects, suggesting their potential as adjunctive therapy for concurrent management of T2DM and PD.

AIM OF THE STUDY

To elucidate the shared mechanisms underlying T2DM and PD, particularly focusing on the potential mechanisms by which medicinal herbs (including herbal formulas, single herbs, and active compounds) may treat these diseases, to provide valuable insights for developing therapeutics targeting comorbid T2DM and PD.

MATERIALS AND METHODS

Studies exploring the mechanisms underlying T2DM and PD, as well as the treatment of these conditions with medicinal herbs, were extracted from several electronic databases, including PubMed, Web of Science, Google Scholar, and China National Knowledge Infrastructure (CNKI).

RESULTS

Numerous studies have shown that inflammation, oxidative stress, insulin resistance, impaired autophagy, gut microbiota dysbiosis, and ferroptosis are shared mechanisms underlying T2DM and PD mediated through the NLRP3 inflammasome, NF-κB, MAPK, Keap1/Nrf2/ARE, PI3K/AKT, AMPK/SIRT1, and System XC--GSH-GPX4 signaling pathways. Thirty-four medicinal herbs, including 2 herbal formulas, 4 single herbs, and 28 active compounds, have been reported to potentially exert anti-T2DM and anti-PD effects by targeting these shared mechanisms.

CONCLUSIONS

Traditional Chinese medicine effectively combats T2DM and PD through shared pathological mechanisms, highlighting their potential for application in treating these comorbid conditions.

Relationship Between Hepatic Iron Concentration and Glycemic Metabolism, Prediabetes, and Type 2 Diabetes: A Systematic Review

CONTEXT

Emerging research has suggested a potential link between high iron levels, indicated by serum ferritin levels, and the development of type 2 diabetes (T2D). However, the role of hepatic iron concentration (HIC) on T2D development and progression is not well understood.

OBJECTIVES

This study aims to systematically review the literature on HIC and/or the degree of hepatic iron overload (HIO) in individuals with prediabetes and/or diagnosed T2D, and to analyze associations between HIC and markers of glucose metabolism.

DATA SOURCES

The databases Medline, PubMed, Embase, CINAHL, and Web of Knowledge were searched for studies published in English from 1999 to March 2024. This review followed the Preferred Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist.

DATA EXTRACTION

Data were extracted following the established eligibility criteria. Study characteristics and biomarkers related to prediabetes, T2D, and HIO were extracted. The risk of bias was analyzed using the Newcastle-Ottawa Scale. Data were stratified by the exposure and analyzed in subgroups according to the outcome. Data regarding the HIC values in controls, individuals with prediabetes, and individuals with T2D and the association estimates between HIC or HIO and markers of glycemic metabolism, prediabetes, or T2D were extracted.

DATA ANALYSIS

A total of 12 studies were identified, and data from 4110 individuals were analyzed. HIO was not consistently observed in prediabetic/T2D populations; however, elevated HIC was frequently observed in prediabetic and T2D individuals, and was associated with the disruption of certain glycemic markers in some cases.

CONCLUSION

The extent of iron overload, as indicated by hepatic iron load, varied among the prediabetic and T2D populations studied. Further research is needed to understand the distribution and regulation of iron in T2D pathology.

New insights into the mechanisms of iron absorption: Iron dextran uptake in the intestines of weaned pigs through glucose transporter 5 (GLUT5) and divalent metal transporter 1 (DMT1) transporters

The purpose of this study was to gain insight into the mechanism of iron dextran (DexFe) absorption in the intestines. A total of 72 piglets (average BW = 7.12 ± 0.75 kg, male to female ratio = 1:1) weaned at 28 d of age were randomly divided into two treatment groups with six replicates for each group. The experimental diets included the basal diet supplemented with 100 mg/kg iron dextran (DexFe group) and the basal diet supplemented with 100 mg/kg FeSO4·H2O (CON group). The experiment lasted for 28 d. The piglets' intestinal iron transport was measured in vitro using an Ussing chamber. Porcine intestinal epithelial cell line (IPEC-J2) cells were used to develop a monolayer cell model that explored the molecular mechanism of DexFe absorption. Results showed that compared to the CON group, the ADG of pigs in the DexFe group was improved (P = 0.022), while the F/G was decreased (P = 0.015). The serum iron concentration, apparent iron digestibility, and iron deposition in the duodenum, jejunum, and ileum were increased (P < 0.05) by dietary DexFe supplementation. Piglets in the DexFe group had higher serum red blood count, hemoglobin, serum iron content, serum ferritin and transferrin levels and lower total iron binding capacity (P < 0.05). In the Ussing chamber test, the iron absorption rate of the DexFe group was greater (P < 0.001) than the CON group, and there was no significant difference between the DexFe group and the glucose group (P > 0.05). Furthermore, when compared to the CON group, DexFe administration improved (P < 0.05) SLC2A5 gene and glucose transporter 5 (GLUT5) protein expression but had no effect (P > 0.05) on SLC11A2 gene or divalent metal transporter 1 (DMT1) protein expression. Once the GLUT5 protein was suppressed, the iron transport rate and apparent permeability coefficient were decreased (P < 0.05) in IPEC-J2 monolayer cell models. The findings suggest the effectiveness of DexFe application in weaned piglets and revealed for the first time that DexFe absorption in the intestine is closely related to the glucose transporter GLUT5 protein channel.

Mechanisms controlling cellular and systemic iron homeostasis

In mammals, hundreds of proteins use iron in a multitude of cellular functions, including vital processes such as mitochondrial respiration, gene regulation and DNA synthesis or repair. Highly orchestrated regulatory systems control cellular and systemic iron fluxes ensuring sufficient iron delivery to target proteins is maintained, while limiting its potentially deleterious effects in iron-mediated oxidative cell damage and ferroptosis. In this Review, we discuss how cells acquire, traffick and export iron and how stored iron is mobilized for iron-sulfur cluster and haem biogenesis. Furthermore, we describe how these cellular processes are fine-tuned by the combination of various sensory and regulatory systems, such as the iron-regulatory protein (IRP)-iron-responsive element (IRE) network, the nuclear receptor co-activator 4 (NCOA4)-mediated ferritinophagy pathway, the prolyl hydroxylase domain (PHD)-hypoxia-inducible factor (HIF) axis or the nuclear factor erythroid 2-related factor 2 (NRF2) regulatory hub. We further describe how these pathways interact with systemic iron homeostasis control through the hepcidin-ferroportin axis to ensure appropriate iron fluxes. This knowledge is key for the identification of novel therapeutic opportunities to prevent diseases of cellular and/or systemic iron mismanagement.

Evaluation of the expression of genes associated with iron metabolism in peripheral blood mononuclear cells from Type 2 diabetes mellitus patients

AIMS

Type 2 Diabetes (T2DM) has been linked to ferroptosis. This study aimed to assess expression levels of genes linked with iron metabolism in peripheral blood mononuclear cells (PBMCs) from T2DM patients and to investigate the association of these expression levels with anthropometric and clinical parameters.

METHODS

Gene expression of iron metabolism genes (Ferritin Light Chain, FTL; Ferritin Heavy Chain, FTH1; Transferrin Receptor, TFRC; Divalent Metal Transporter 1, SLC11A2; Ferroportin, SLC40A1) in archival PBMCs was assessed using quantitative real-time PCR assays. Correlations of gene expression with anthropometric/biochemical patient data were evaluated.

RESULTS

The study included 36 (18 male/18 female) T2DM patients and 45 (28 male/17 female) normoglycemic (NGT) subjects with a mean age of 38.1 ± 6.8 years and 47.6 ± 8.6 years respectively. Relative expression of FTL was significantly lower in T2DM females compared to that in NGT females (P = 0.027). Relative expression of SLC40A1 was significantly lower in the T2DM group (P = 0.043) and in the T2DM females (P = 0.021). Relative expression of SLC11A2 was negatively correlated with systolic blood pressure in T2DM male patients. Relative expression of SLC40A1 was negatively associated with serum phosphorous and positively associated with serum thyroid stimulating hormone in male T2DM patients.

CONCLUSIONS

Our findings indicate a reduction in the expression of FTL in perimenopausal T2DM females. Also, in male T2DM patients and NGT subjects, biochemical markers are significantly correlated with the expression of FTL, FTH1, SLC11A2, and SLC40A1 in PBMCs.

Assessing metal ion transporting activity of ZIPs: Intracellular zinc and iron detection

Zrt/Irt-like proteins (ZIPs or SLC39A) are a large family of metal ion transporters mainly responsible for zinc uptake. Some ZIPs have been shown to specifically transport zinc, whereas others have broader substrate specificity in divalent metal ion trafficking, notably those of zinc and iron ions. Measuring intracellular zinc and iron levels helps assess their molecular and physiological activities. This chapter presents step-by-step methods for evaluating intracellular metal ion concentrations, including direct measurement using inductively coupled plasma-mass spectrometry (ICP-MS), chemical staining, fluorescent probes, and indirect reporter assays such as activity analysis of enzymes whose activities are dependent on metal ion availability.

Dysmetabolic Iron Overload Syndrome: Going beyond the Traditional Risk Factors Associated with Metabolic Syndrome

Dysmetabolic iron overload syndrome (DIOS) corresponds to the increase in iron stores associated with components of metabolic syndrome (MtS) and in the absence of an identifiable cause of iron excess. The objective of this work was to review the main aspects of DIOS. PUBMED and EMBASE were consulted, and PRISMA guidelines were followed. DIOS is usually asymptomatic and can be diagnosed by investigating MtS and steatosis. About 50% of the patients present altered hepatic biochemical tests (increased levels of γ-glutamyl transpeptidase itself or associated with increased levels of alanine aminotransferase). The liver may present parenchymal and mesenchymal iron overload, but the excess of iron is commonly mild. Steatosis or steatohepatitis is observed in half of the patients. Fibrosis is observed in about 15% of patients. Hyperferritinemia may damage the myocardium, liver, and several other tissues, increasing morbidity and mortality. Furthermore, DIOS is closely related to oxidative stress, which is closely associated with several pathological conditions such as inflammatory diseases, hypertension, diabetes, heart failure, and cancer. DIOS is becoming a relevant finding in the general population and can be associated with high morbidity/mortality. For these reasons, investigation of this condition could be an additional requirement for the early prevention of cardiovascular diseases.