Hepcidin is directly regulated by insulin and plays an important role in iron overload in streptozotocin-induced diabetic rats

Glucose induced regulation of iron transporters implicates kidney iron accumulation

Increased iron level is detected in rat kidney and human urine in diabetic condition and implicated in associated nephropathy. However, the biological cue and mechanism of the iron accumulation remain unclear. Here we reveal that glucose increases iron uptake by promoting transferrin receptor 1 (TFRC) in kidney cells by a translational mechanism but does not alter expression of endosomal iron transporter DMT1. Glucose decreases iron exporter ferroportin (FPN) by a protein degradation mechanism. Hepcidin is known to bind at Cys-326 residue in promoting degradation of human ferroportin. When Cys-326 was mutated to Ser in human-FPN-FLAG and expressed in kidney cells, glucose still could degrade FPN-FLAG implicating involvement of hepcidin independent mechanism in glucose induced ferroportin degradation. Chronic hyperglycemia was generated in rats by administering streptozotocin (STZ) with periodic insulin injection to determine the level of iron homeostasis components. Increased TFRC and decreased ferroportin levels were detected in hyperglycemic rat kidney by Western blot and immunohistochemistry analyses. Hepcidin mRNA was not significantly altered in kidney but was marginally decreased in liver. Perls' staining and non-heme iron estimation showed an elevated iron level in hyperglycemic rat kidney. These results suggest that high glucose dysregulates iron transport components resulting iron accumulation in diabetic kidney.

Serum Uric Acid and Iron Status: Exploring a Complex Interaction in Metabolic Syndrome Patients of Eastern India

BACKGROUND

Metabolic syndrome, a cluster of illnesses including insulin resistance, hyperlipidemia, hypertension, and central obesity, is affecting roughly a quarter of the world population. Dysregulation of iron homeostasis may be associated with insulin resistance, leading to metabolic syndrome. Uric acid is an antioxidant currently studied in relation to several metabolic disorders. It may also be interlinked with iron metabolism. Yet, data regarding the interplay between serum iron, ferritin, and uric acid in metabolic syndrome are scarce. Hence, this study aimed to identify any alteration of serum iron, ferritin, and uric acid levels in metabolic syndrome patients of Eastern India and to explore any inter-relationship between these parameters.  Methodology: A cross-sectional observational study including 103 patients suffering from metabolic syndrome and 107 age- and sex-matched healthy individuals was conducted. Subjects were evaluated for serum iron, ferritin, and uric acid levels, besides the diagnostic parameters of metabolic syndrome.

RESULTS

Metabolic syndrome cases had higher serum iron, ferritin, and uric acid levels as compared to the controls. Serum uric acid was positively correlated with both iron and ferritin.

CONCLUSION

Metabolic syndrome is associated with elevated serum levels of iron, ferritin, and uric acid. Iron overload, reflected in elevated serum ferritin, can cause oxidative stress and endothelial damage, thereby predisposing to metabolic and vascular complications. Uric acid, an antioxidant, can rise in an attempt to counter oxidative stress. Metabolic syndrome patients should be periodically assessed for iron profile and uric acid to design suitable treatment protocols for better management of disease progression and alleviation of complications.

Targeting PKCα alleviates iron overload in diabetes and hemochromatosis through the inhibition of ferroportin

ABSTRACT

Ferroportin (Fpn) is the only iron exporter, playing a crucial role in systemic iron homeostasis. Fpn is negatively regulated by its ligand hepcidin, but other potential regulators in physiological and disease conditions remain poorly understood. Diabetes is a metabolic disorder that develops body iron loading with unknown mechanisms. By using diabetic mouse models and human duodenal specimens, we demonstrated that intestinal Fpn expression was increased in diabetes in a hepcidin-independent manner. Protein kinase C (PKC) is hyperactivated in diabetes. We showed that PKCα was required to sustain baseline Fpn expression and diabetes-induced Fpn upregulation in the enterocytes and macrophages. Knockout of PKCα abolished diabetes-associated iron overload. Mechanistically, activation of PKCα increased the exocytotic trafficking of Fpn and decreased the endocytic trafficking of Fpn in the resting state. Hyperactive PKCα also suppressed hepcidin-induced ubiquitination, internalization, and degradation of Fpn. We further observed that iron loading in the enterocytes and macrophages activated PKCα, acting as a novel mechanism to enhance Fpn-dependent iron efflux. Finally, we demonstrated that the loss-of-function of PKCα and pharmacological inhibition of PKC significantly alleviated hereditary hemochromatosis-associated iron overload. Our study has highlighted, to our knowledge, for the first time, that PKCα is an important positive regulator of Fpn and a new target in the control of iron homeostasis.

Iron chelation mitigates mitochondrial dysfunction and oxidative stress by enhancing nrf2-mediated antioxidant responses in the renal cortex of a murine model of type 2 diabetes

Renal iron overload is a common complication of diabetes that leads to oxidative stress and mitochondrial dysfunction in the kidneys. This study investigated the effects of iron chelation using deferiprone on mitochondrial dysfunction and oxidative stress in the renal cortex of a murine model of type 2 diabetes. Diabetic rats were treated with deferiprone (50 mg/kg BW) for 16 weeks. Our results show that iron chelation with deferiprone significantly increased the nuclear accumulation of Nrf2, a transcription factor that regulates the expression of antioxidant enzymes. This led to enhanced antioxidant capacity, reduced production of reactive oxygen species, and improved mitochondrial bioenergetic function in diabetic rats. However, chronic iron chelation led to altered mitochondrial respiration and increased oxidative stress in non-diabetic rats. In conclusion, our findings suggest that iron chelation with deferiprone protects mitochondrial bioenergetics and mitigates oxidative stress in the renal cortex, involving the NRF2 pathway in type 2 diabetes.

Serum ferritin level and associated factors among uncontrolled adult type II diabetic follow-up patients: comparative based cross-sectional study

BACKGROUND

Uncontrolled type 2 diabetes mellitus (UT2DM) and its associated consequences nowadays have been a global health crisis, especially for adults. Iron has the property to oxidize and reduce reversibly, which is necessary for metabolic processes and excess accumulation of iron indicated by serum ferritin levels could have a significant impact on the pathophysiology of T2DM via generation of reactive oxygen species (ROS). However, no conclusive evidence existed about the association of serum ferritin with the state of glycemic control status. Therefore, this study aimed to evaluate serum ferritin levels and associated factors in uncontrolled T2DM patients and compare them with those of controlled T2DM and non-diabetic control groups.

METHODS

A hospital-based comparative cross-sectional study was conducted among conveniently selected 156 study participants, who were categorized into three equal groups of uncontrolled T2DM, controlled T2DM, and non-diabetic control groups from October 2 to December 29, 2023 at St. Paul's Hospital Millennium Medical College. A pre-tested structured questionnaire was used to collect socio-demographic and diabetes-related information. The laboratory tests were done using an automated chemistry analyzer and IBM-SPSS statistical software (version-27) was utilized for data entry and analysis with a significance level of p < 0.05.

RESULT

The mean serum ferritin level was noticeably higher in uncontrolled T2DM patients as compared to controlled T2DM and control groups (p < 0.001). It was significantly correlated with HbA1c [r = 0.457, p < 0.001], fasting blood sugar (FBs) [r = 0.386, p < 0.001], serum iron [r = 0.430, p < 0.001], and systolic blood pressure (SBP) [r = 0.195, p = 0.047] in T2DM patients. A multivariate logistic regression model revealed that a rise in HbA1c (AOR = 3.67, 95% CI(1.50-8.98), serum iron (AOR = 1.02, 95% CI(1.01-1.04), male gender (AOR = 0.16, 95% CI(0.05-0.57) and being on oral hypoglycemic agent (OHA) monotherapy (AOR = 0.26, 95% CI(0.07-0.95) were key associated factors for the elevated serum ferritin among T2DM patients.

CONCLUSION

The present study demonstrated that T2DM patients had elevated serum ferritin levels which might be related to the existence of long-term hyperglycaemia and that serum ferritin had a significant positive association with HbA1c and FBs, implying that it could be used as an additional biomarker to predict uncontrolled T2DM patients.

Effects of Diabetes Mellitus on Corneal Immune Cell Activation and the Development of Keratopathy

Diabetes mellitus (DM) is one of the most prevalent diseases globally, and its prevalence is rapidly increasing. Most patients with a long-term history of DM present with some degree of keratopathy (DK). Despite its high incidence, the underlying inflammatory mechanism of DK has not been elucidated yet. For further insights into the underlying immunopathologic processes, we utilized streptozotocin-induced mice to model type 1 DM (T1D) and B6.Cg-Lepob/J mice to model type 2 DM (T2D). We evaluated the animals for the development of clinical manifestations of DK. Four weeks post-induction, the total frequencies of corneal CD45+CD11b+Ly-6G- myeloid cells, with enhanced gene and protein expression levels for the proinflammatory cytokines TNF-α and IL-1β, were higher in both T1D and T2D animals. Additionally, the frequencies of myeloid cells/mm2 in the sub-basal neural plexus (SBNP) were significantly higher in T1D and T2D compared to non-diabetic mice. DK clinical manifestations were observed four weeks post-induction, including significantly lower tear production, corneal sensitivity, and epitheliopathy. Nerve density in the SBNP and intraepithelial terminal endings per 40x field were lower in both models compared to the normal controls. The findings of this study indicate that DM alters the immune quiescent state of the cornea during disease onset, which may be associated with the progressive development of the clinical manifestations of DK.

Interplay between gut microbiota and the master iron regulator, hepcidin, in the pathogenesis of liver fibrosis

INTRODUCTION

There is a proven role for hepcidin and the composition of gut microbiota and its derivatives in the pathophysiology of liver fibrosis.

AREA COVERED

This review focuses on the literature search regarding the effect of hepcidin and gut microbiota on regulating liver physiology. We presented the regulating mechanisms of hepcidin expression and discussed the possible interaction between gut microbiota and hepcidin regulation. Furthermore, we investigated the importance of the hepcidin gene in biological processes and bacterial interactions using bioinformatics analysis.

EXPERT OPINION

One of the main features of liver fibrosis is iron accumulation in hepatic cells, including hepatocytes. This accumulation can induce an oxidative stress response, inflammation, and activation of hepatic stellate cells. Hepcidin is a crucial regulator of iron by targeting ferroportin expressed on hepatocytes, macrophages, and enterocytes. Various stimuli, such as iron load and inflammatory signals, control hepcidin regulation. Furthermore, a bidirectional relationship exists between iron and the composition and metabolic activity of gut microbiota. We explored the potential of gut microbiota to influence hepcidin expression and potentially manage liver fibrosis, as the regulation of iron metabolism plays a crucial role in this context.

Association of iron homeostasis biomarkers in type 2 diabetes and glycaemic traits: a bidirectional two-sample Mendelian randomization study

BACKGROUND

Mendelian randomization (MR) studies show iron positively associated with type 2 diabetes (T2D) but included potentially biasing hereditary haemochromatosis variants and did not assess reverse causality.

METHODS

We assessed the relation of iron homeostasis with T2D and glycaemic traits bidirectionally, using genome-wide association studies (GWAS) of iron homeostasis biomarkers [ferritin, serum iron, total iron-binding capacity (TIBC), transferrin saturation (TSAT) (n ≤ 246 139)], T2D (DIAMANTE n = 933 970 and FinnGen n = 300 483), and glycaemic traits [fasting glucose (FG), 2-h glucose, glycated haemoglobin (HbA1c) and fasting insulin (FI) (n ≤ 209 605)]. Inverse variance weighting (IVW) was the main analysis, supplemented with sensitivity analyses and assessment of mediation by hepcidin.

RESULTS

Iron homeostasis biomarkers were largely unrelated to T2D, although serum iron was potentially associated with higher T2D [odds ratio: 1.07 per standard deviation; 95% confidence interval (CI): 0.99 to 1.16; P-value: 0.078) in DIAMANTE only. Higher ferritin, serum iron, TSAT and lower TIBC likely decreased HbA1c, but were not associated with other glycaemic traits. Liability to T2D likely increased TIBC (0.03 per log odds; 95% CI: 0.01 to 0.05; P-value: 0.005), FI likely increased ferritin (0.29 per log pmol/L; 95% CI: 0.12 to 0.47; P-value: 8.72 x 10-4). FG likely increased serum iron (0.06 per mmol/L; 95% CI: 0.001 to 0.12; P-value: 0.046). Hepcidin did not mediate these associations.

CONCLUSION

It is unlikely that ferritin, TSAT and TIBC cause T2D although an association for serum iron could not be excluded. Glycaemic traits and liability to T2D may affect iron homeostasis, but mediation by hepcidin is unlikely. Corresponding mechanistic studies are warranted.

Insulin augments angiotensin II-induced myocardial fibrosis via the MEK/STAT3 pathway

Regular insulin therapy is significantly related to worse cardiovascular outcomes in patients with type 2 diabetes and heart failure. However, the mechanisms of the causal relationship remain unclear. In this study, we observed the effect of insulin on cardiac structure and function and found that insulin dramatically augmented angiotensin II (Ang II)-induced cardiac dysfunction, as well as the proliferation and collagen production of primary cardiac fibroblasts. Total STAT3 expression, but not activation was stimulated by insulin; the effect of insulin on Ang II-induced fibrosis disappeared when STAT3 was blocked and could be entirely suppressed by the MEK inhibitor PD0325901. Our findings suggest a noninsulin-dependent glucose-lowering regimen for patients with type 2 diabetes (T2DM) and heart failure (HF).

Targeting PKC alleviates iron overload in diabetes and hemochromatosis

Diabetes is one of the most prevalent chronic diseases worldwide. Iron overload increases the incidence of diabetes and aggravates diabetic complications that cause mortality. Reciprocally, diabetes potentially promotes body iron loading, but the mechanism remains not well understood. In this study, we demonstrated systemic iron excess and the upregulation of iron exporter ferroportin (Fpn) in the enterocytes and macrophages of multiple diabetic mouse models. Increased Fpn expression and iron efflux was also seen in the enterocytes of type 2 diabetic human patients. We further showed that protein kinase C (PKC), which is activated in hyperglycemia, was responsible for the sustained membrane expression of Fpn in physiological and in diabetic settings. For the first time, we identified that PKCs were novel binding proteins and positive regulators of Fpn. Mechanistically, hyperactive PKC promoted exocytotic membrane insertion while inhibited the endocytic trafficking of Fpn in the resting state. PKC also protected Fpn from internalization and degradation by its ligand hepcidin dependent on decreased ubiquitination and increased phosphorylation of Fpn. Importantly, the loss-of-function and pharmacological inhibition of PKC alleviated systemic iron overload in diabetes and hemochromatosis. Our study thus highlights PKC as a novel target in the control of systemic iron homeostasis.

The Role of Iron Overload in Diabetic Cognitive Impairment: A Review

It is well documented that diabetes mellitus (DM) is strongly associated with cognitive decline and structural damage to the brain. Cognitive deficits appear early in DM and continue to worsen as the disease progresses, possibly due to different underlying mechanisms. Normal iron metabolism is necessary to maintain normal physiological functions of the brain, but iron deposition is one of the causes of some neurodegenerative diseases. Increasing evidence shows that iron overload not only increases the risk of DM, but also contributes to the development of cognitive impairment. The current review highlights the role of iron overload in diabetic cognitive impairment (DCI), including the specific location and regulation mechanism of iron deposition in the diabetic brain, the factors that trigger iron deposition, and the consequences of iron deposition. Finally, we also discuss possible therapies to improve DCI and brain iron deposition.

Differences in DNA methylation of HAMP in blood cells predicts the development of type 2 diabetes

OBJECTIVES

Better disease management can be achieved with earlier detection through robust, sensitive, and easily accessible biomarkers. The aim of the current study was to identify novel epigenetic biomarkers determining the risk of type 2 diabetes (T2D).

METHODS

Livers of 10-week-old female New Zealand Obese (NZO) mice, slightly differing in their degree of hyperglycemia and liver fat content and thereby in their diabetes susceptibility were used for expression and methylation profiling. We screened for differences in hepatic expression and DNA methylation in diabetes-prone and -resistant mice, and verified a candidate (HAMP) in human livers and blood cells. Hamp expression was manipulated in primary hepatocytes and insulin-stimulated pAKT was detected. Luciferase reporter assays were conducted in a murine liver cell line to test the impact of DNA methylation on promoter activity.

RESULTS

In livers of NZO mice, the overlap of methylome and transcriptome analyses revealed a potential transcriptional dysregulation of 12 hepatokines. The strongest effect with a 52% decreased expression in livers of diabetes-prone mice was detected for the Hamp gene, mediated by elevated DNA methylation of two CpG sites located in the promoter. Hamp encodes the iron-regulatory hormone hepcidin, which had a lower abundance in the livers of mice prone to developing diabetes. Suppression of Hamp reduces the levels of pAKT in insulin-treated hepatocytes. In liver biopsies of obese insulin-resistant women, HAMP expression was significantly downregulated along with increased DNA methylation of a homologous CpG site. In blood cells of incident T2D cases from the prospective EPIC-Potsdam cohort, higher DNA methylation of two CpG sites was related to increased risk of incident diabetes.

CONCLUSIONS

We identified epigenetic changes in the HAMP gene which may be used as an early marker preceding T2D.

Iron, glucose and fat metabolism and obesity: an intertwined relationship

A bidirectional relationship exists between adipose tissue metabolism and iron regulation. Total body fat, fat distribution and exercise influence iron status and components of the iron-regulatory pathway, including hepcidin and erythroferrone. Conversely, whole body and tissue iron stores associate with fat mass and distribution and glucose and lipid metabolism in adipose tissue, liver, and muscle. Manipulation of the iron-regulatory proteins erythroferrone and erythropoietin affects glucose and lipid metabolism. Several lines of evidence suggest that iron accumulation and metabolism may play a role in the development of metabolic diseases including obesity, type 2 diabetes, hyperlipidaemia and non-alcoholic fatty liver disease. In this review we summarise the current understanding of the relationship between iron homoeostasis and metabolic disease.

Multifunctional Fe3O4-PEI@HA nanoparticles in the ferroptosis treatment of hepatocellular carcinoma through modulating reactive oxygen species

Ferroptosis is a novel form of regulated cell death induced by iron-dependent lipid peroxidation imbalance. It has emerged as a promising antitumor therapeutic strategy in recent years. In this work, we successfully synthesized a complex magnetic nanocube Fe₃O₄ modified with PEI and HA by the thermal decomposition method. While loading a ferroptosis inducer RSL3 inhibited cancer cells through the ferroptosis signal transduction pathway. The drug delivery system could actively target tumor cells through an external magnetic field and HA-CD44 binding. Zeta potential analysis showed that Fe₃O₄-PEI@HA-RSL3 nanoparticles were more stable and uniformly dispersed in tumor acidic environment. Moreover, cellular experiments demonstrated that Fe₃O₄-PEI@HA-RSL3 nanoparticles could significantly inhibit the proliferation of hepatoma cells without a cytotoxic effect on normal hepatic cells. In addition, Fe₃O₄-PEI@HA-RSL3 played a vital role in ferroptosis by accelerating ROS production. The expression of ferroptosis-related genes Lactoferrin, FACL 4, GPX 4 and Ferritin was significantly suppressed with increasing treatment of Fe₃O₄-PEI@HA-RSL3 nanocubes. Therefore, this ferroptosis nanomaterial has great potential in Hepatocellular carcinoma (HCC) therapy.

Systemic Anti-Inflammatory Therapy Aided by Curcumin-Laden Double-Headed Nanoparticles Combined with Injectable Long-Acting Insulin in a Rodent Model of Diabetes Eye Disease

Therapeutic interventions that counter emerging targets in diabetes eye diseases are lacking. We hypothesize that a combination therapy targeting inflammation and hyperglycemia can prevent diabetic eye diseases. Here, we report a multipronged approach to prevent diabetic cataracts and retinopathy by combining orally bioavailable curcumin-laden double-headed (two molecules of gambogic acid conjugated to terminal carboxyl groups of poly(d,l-lactide-co-glycolide)) nanoparticles and injectable basal insulin. The combination treatment led to a significant delay in the progression of diabetic cataracts and retinopathy, improving liver function and peripheral glucose homeostasis. We found a concurrent reduction in lens aggregate protein, AGEs, and increased mitochondrial ATP production. Importantly, inhibition of Piezo1 protected against hyperglycemia-induced retinal vascular damage suggesting possible involvement of Piezo1 in the regulation of retinal phototransduction. Histologic evaluation of murine small intestines revealed that chronic administration of curcumin-laden double-headed nanoparticles was well tolerated, circumventing the fear of nanoparticle toxicity. These findings establish the potential of anti-inflammatory and anti-hyperglycemic combination therapy for the prevention of diabetic cataracts and retinopathy.

Iron as a therapeutic target in chronic liver disease

It was clearly realized more than 50 years ago that iron deposition in the liver may be a critical factor in the development and progression of liver disease. The recent clarification of ferroptosis as a specific form of regulated hepatocyte death different from apoptosis and the description of ferritinophagy as a specific variation of autophagy prompted detailed investigations on the association of iron and the liver. In this review, we will present a brief discussion of iron absorption and handling by the liver with emphasis on the role of liver macrophages and the significance of the iron regulators hepcidin, transferrin, and ferritin in iron homeostasis. The regulation of ferroptosis by endogenous and exogenous mod-ulators will be examined. Furthermore, the involvement of iron and ferroptosis in various liver diseases including alcoholic and non-alcoholic liver disease, chronic hepatitis B and C, liver fibrosis, and hepatocellular carcinoma (HCC) will be analyzed. Finally, experimental and clinical results following interventions to reduce iron deposition and the promising manipulation of ferroptosis will be presented. Most liver diseases will be benefited by ferroptosis inhibition using exogenous inhibitors with the notable exception of HCC, where induction of ferroptosis is the desired effect. Current evidence mostly stems from in vitro and in vivo experimental studies and the need for well-designed future clinical trials is warranted.

Role of ferroptosis inhibitors in the management of diabetes

Ferroptosis, the iron-dependent, lipid peroxide-mediated cell death, has garnered attention due to its critical involvement in crucial physiological and pathological cellular processes. Indeed, several studies have attributed its role in developing a range of disorders, including diabetes. As accumulating evidence further the understanding of ferroptotic mechanisms, the impact this specialized mode of cell death has on diabetic pathogenesis is still unclear. Several in vivo and in vitro studies have highlighted the association of ferroptosis with beta-cell death and insulin resistance, supported by observations of marked alterations in ferroptotic markers in experimental diabetes models. The constant improvement in understanding ferroptosis in diabetes has demonstrated it as a potential therapeutic target in diabetic management. In this regard, ferroptosis inhibitors promise to rescue pancreatic beta-cell function and alleviate diabetes and its complications. This review article elucidates the key ferroptotic pathways that mediate beta-cell death in diabetes, and its complications. In particular, we share our insight into the cross talk between ferroptosis and other hallmark pathogenic mediators such as oxidative and endoplasmic reticulum stress regulators relevant to diabetes progression. Further, we extensively summarize the recent developments on the role of ferroptosis inhibitors and their therapeutic action in alleviating diabetes and its complications.

Tracking hepcidin level in induced type 2 diabetic rats and how Empagliflozin affects its level

BACKGROUND

Hepcidin is a hormone that contributes to iron homeostasis, produced either through hepatic or extrahepatic pathways. Its production may be affected by proinflammatory mediators released by macrophages, which play a role in the development of peripheral insulin resistance. Insulin itself may increase the production of hepcidin hormone from pancreatic β-cells.

OBJECTIVES

To evaluate the impact of induction of type 2 diabetes mellitus (T2DM) in albino wister rats on the level of hepcidin. Also, to examine the role of 2-week use of Empagliflozin, a sodium-glucose cotransporter-2 inhibitor (SGLT2 Inhibitor), on the hepcidin level comparing to control.

METHOD

An interventional study includes randomization of 36 rats into three groups (A: negative control, B: positive control, and C: Empagliflozin group). Two rats were excluded from the study for different reasons. T2DM was induced using high-fat diet/high-sugar diet (HFD/HSD) for 8 weeks. Empagliflozin was then given to Group C for 2 weeks at a dose of 35 mg/kg/day. Hepcidin level was determined at the baseline, and at week 8 and week 10 intervals. Hepcidin was determined using enzyme-linked immunosorbent assay (ELISA).

RESULTS

Hepcidin level significantly increased following the induction of T2DM in both B and C Groups. Hepcidin level in Group B insignificantly reduced 2 weeks after discontinuation of HFD/HSD and significantly reduced in Group C. Group A experienced no statistical difference in hepcidin level at week 10 when compared to baseline.

CONCLUSION

Induction of T2DM is associated with a significant increase in the level of hepcidin. Empagliflozin significantly reduced hepcidin level in newly induced diabetic rats.

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

Iron is critical for the appearance and maintenance of life on Earth. Almost all organisms compete or cooperate for iron acquisition, demonstrating the importance of this essential element for the biological and physiological processes that are key for the preservation of metabolic homeostasis. In humans and other mammals, the bidirectional interactions between the bacterial component of the gut microbiota and the host for iron acquisition shape both host and microbiota metabolism. Bacterial functions influence host iron absorption, whereas the intake of iron, iron deficiency and iron excess in the host affect bacterial biodiversity, taxonomy and function, resulting in changes in bacterial virulence. These consequences of the host-microbial crosstalk affect systemic levels of iron, its storage in different tissues and host glucose metabolism. At the interface between the host and the microbiota, alterations in the host innate immune system and in circulating soluble factors that regulate iron (that is, hepcidin, lipocalin 2 and lactoferrin) are associated with metabolic disease. In fact, patients with obesity-associated metabolic dysfunction and insulin resistance exhibit dysregulation in iron homeostasis and alterations in their gut microbiota profile. From an evolutionary point of view, the pursuit of two important nutrients - glucose and iron - has probably driven human evolution towards the most efficient pathways and genes for human survival and health.

Paying the Iron Price: Liver Iron Homeostasis and Metabolic Disease

Iron is an essential metal element whose bioavailability is tightly regulated. Under normal conditions, systemic and cellular iron homeostases are synchronized for optimal function, based on the needs of each system. During metabolic dysfunction, this synchrony is lost, and markers of systemic iron homeostasis are no longer coupled to the iron status of key metabolic organs such as the liver and adipose tissue. The effects of dysmetabolic iron overload syndrome in the liver have been tied to hepatic insulin resistance, nonalcoholic fatty liver disease, and nonalcoholic steatohepatitis. While the existence of a relationship between iron dysregulation and metabolic dysfunction has long been acknowledged, identifying correlative relationships is complicated by the prognostic reliance on systemic measures of iron homeostasis. What is lacking and perhaps more informative is an understanding of how cellular iron homeostasis changes with metabolic dysfunction. This article explores bidirectional relationships between different proteins involved in iron homeostasis and metabolic dysfunction in the liver. © 2022 American Physiological Society. Compr Physiol 12:3641-3663, 2022.

Melatonin Regulates Iron Homeostasis by Inducing Hepcidin Expression in Hepatocytes

The pineal hormone, melatonin, plays important roles in circadian rhythms and energy metabolism. The hepatic peptide hormone, hepcidin, regulates iron homeostasis by triggering the degradation of ferroportin (FPN), the protein that transfers cellular iron to the blood. However, the role of melatonin in the transcriptional regulation of hepcidin is largely unknown. Here, we showed that melatonin upregulates hepcidin gene expression by enhancing the melatonin receptor 1 (MT1)-mediated c-Jun N-terminal kinase (JNK) activation in hepatocytes. Interestingly, hepcidin gene expression was increased during the dark cycle in the liver of mice, whereas serum iron levels decreased following hepcidin expression. In addition, melatonin significantly induced hepcidin gene expression and secretion, as well as the subsequent FPN degradation in hepatocytes, which resulted in cellular iron accumulation. Melatonin-induced hepcidin expression was significantly decreased by the melatonin receptor antagonist, luzindole, and by the knockdown of MT1. Moreover, melatonin activated JNK signaling and upregulated hepcidin expression, both of which were significantly decreased by SP600125, a specific JNK inhibitor. Chromatin immunoprecipitation analysis showed that luzindole significantly blocked melatonin-induced c-Jun binding to the hepcidin promoter. Finally, melatonin induced hepcidin expression and secretion by activating the JNK-c-Jun pathway in mice, which were reversed by the luzindole treatment. These findings reveal a previously unrecognized role of melatonin in the circadian regulation of hepcidin expression and iron homeostasis.

Interplay of serum hepcidin with female sex hormones, metabolic syndrome, and abdominal fat distribution among premenopausal and postmenopausal women

Background and purpose

Hepcidin is the central regulatory molecule of systemic iron homeostasis. Serum ferritin, insulin resistance (IR) and metabolic syndrome (MetS), female sex hormones, and abdominal fat distribution are related to each other and all are linked to menopausal state. Our study was the first to assess the impact of these parameters on hepcidin level among premenopausal women (group I) during the early follicular phase (group I-F) and mid-luteal-phase (group I-L) of the same reproductive cycle and among postmenopausal women (group II). Serum iron parameters, estrogen, progesterone and hepcidin, and plasma insulin were assessed. Abdominal subcutaneous fat (SCF) and peritoneal visceral fat (PVF) thickness were measured by unenhanced- CT. Group I and group II were divided into MetS and non-MetS subgroups.

Results

The entire group II and MetS-stratified subgroups had significant higher hepcidin level than corresponding group I-F and group I-L. Group I-L had significant higher hepcidin than group I-F. Among group I-F, group I-L, and group II, MetS subgroups had higher hepcidin but not hepcidin/ ferritin ratio (H/F) than corresponding non-MetS; and hepcidin had positive correlations with ferritin, insulin, IR, and SCF. In group I-F and group II, hepcidin had positive correlations with estrogen and progesterone; hepcidin levels increase significantly and linearly with increasing number of MetS features; and cut off values of hepcidin for prediction of MetS were 5.8 ≥ and ≥ 10.3 ng/ml respectively. Main contributors to hepcidin were iron and ferritin in all groups, SCF and progesterone in group I-F, and insulin, progesterone, and MetS in group II. H/F ratio was higher in group II.

Conclusion

Postmenopausal state (postMS), MetS, and luteal phase are independently associated with high hepcidin level. Serum iron parameters (iron and ferritin) as main regulators of hepcidin are preserved regardless of menopausal state. Its regulation differs based on menopausal state: IR, MetS, and progesterone in postMS meanwhile abdominal SCF and progesterone in premenopausal states. Despite positive associations of estrogen and progesterone with hepcidin, they do not explain its higher level in postMS. Hepcidin levels linearly increase with number of Mets feature and it had high sensitivity for diagnosis of MetS.

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.

Serum ferritin as a risk factor for type 2 diabetes mellitus, regulated by liver transferrin receptor 2

OBJECTIVE

The aim of this study was to evaluate the effect of TFR2 on iron storage in type 2 diabetes.

METHODS

A cross-sectional study was conducted among 1938 participants from the Jiangchuan Community of Shanghai. A total of 784 participants with T2DM and 1154 normal participants (non-T2DM) were enrolled in this study. Serum ferritin, fasting blood glucose, postprandial blood glucose, and HbA1C (glycated hemoglobin A1c) levels were determined. Eighteen Wistar male rats were randomly assigned into three groups (n = 6/group): rats in a high-fat diet streptozotocin (HFD+STZ) group were fed with HFD for 4 weeks and intraperitoneally injected with streptozotocin (STZ); rats in a control group were fed with a standard diet for 4 weeks and intraperitoneally injected with buffer; rats in an STZ group were fed with a standard diet for 4 weeks and intraperitoneally injected with streptozotocin. Glucose tolerance test was performed at the end of the study. Blood samples and liver tissues were assessed for liver TFR2, blood glucose, serum ferritin, and iron levels.

RESULTS

The mean serum ferritin level of T2DM participants was significantly higher than that of the control group (227 (140-352) vs 203.5 (130.5-312) ng/mL, P < 0.05). Serum ferritin level was an independent risk factor for T2DM (high ferritin group vs low ferritin group, 1.304 (1.03-1.651), P < 0.05). Diabetic rats showed reduced liver TFR2 levels, with increased serum ferritin levels.

CONCLUSION

T2DM participants exhibited iron disorder with elevated serum ferritin levels. Elevated serum ferritin levels in diabetic rats were accompanied by reduced liver TFR2 levels.

Targeting Ferroptosis for Lung Diseases: Exploring Novel Strategies in Ferroptosis-Associated Mechanisms

Ferroptosis is an iron-dependent regulated necrosis characterized by the peroxidation damage of lipid molecular containing unsaturated fatty acid long chain on the cell membrane or organelle membrane after cellular deactivation restitution system, resulting in the cell membrane rupture. Ferroptosis is biochemically and morphologically distinct and disparate from other forms of regulated cell death. Recently, mounting studies have investigated the mechanism of ferroptosis, and numerous proteins play vital roles in regulating ferroptosis. With detailed studies, emerging evidence indicates that ferroptosis is found in multiple lung diseases, demonstrating that ferroptosis appears to be particularly important for lung diseases. The mounting interest in ferroptosis drugs specifically targeting the ferroptosis mechanism holds substantial therapeutic promise in lung diseases. The present review emphatically summarizes the functions and integrated molecular mechanisms of ferroptosis in various lung diseases, proposing that multiangle regulation of ferroptosis might be a promising strategy for the clinical treatment of lung diseases.

Evidence of dysregulated iron homeostasis in newly diagnosed diabetics, but not in pre-diabetics

AIM

Diabetes mellitus has been reported to be associated with increased serum levels of ferritin. The basis of this association is unclear. It is also not precisely known whether other iron-related parameters, including hepcidin (the central regulator of systemic iron homeostasis), are affected under these circumstances. This study attempted to determine this.

METHODS

Adult men (normoglycemic or newly diagnosed with diabetes or pre-diabetes) were recruited. Anthropometric, metabolic, and hematological and iron-related parameters in blood were measured. Indices of insulin resistance (HOMA-IR) and pancreatic beta cell function (HOMA-β) were calculated.

RESULTS

Subjects in the 3 groups were similar in age, and anthropometric and hematological parameters. Serum ferritin and hepcidin levels were higher in diabetics, than in pre-diabetics and in control subjects. These elevations seen were not linked to the presence of inflammation. HOMA-IR was higher in diabetics, and HOMA-β lower in diabetics and pre-diabetics, than in control subjects. HOMA-IR and serum ferritin were positively correlated with one another.

CONCLUSION

Elevated levels of serum ferritin and hepcidin in newly diagnosed diabetics (but not pre-diabetics) indicate dysregulated iron homeostasis, with the former positively associated with insulin resistance in these patients.

Targetting ferroptosis for blood cell-related diseases

Ferroptosis is an iron-dependent cell death pathway and participates in various diseases. Current evidence suggests that ferroptosis can obviously affect the function of blood cells. This paper aims to elaborate the role of ferroptosis in blood cells and related diseases. First, abnormal ferroptosis damages the developing red blood cells by breaking systemic iron homeostasis, leading to erythropoiesis suppression and anaemia. Ferroptosis mediates neutrophils recruitment and neutrophil extracellular trap formation (NETosis). In T-cells, ferroptosis induces a novel point of synergy between immunotherapy and radiotherapy. Additionally, ferroptosis may mediate B cells differentiation, antibody responses and lymphoma. Nevertheless, increased ferroptosis can ameliorate acute myeloid leukaemia and T-cell leukaemia/lymphoma by inducing iron-dependent cancer cells death. Besides, ferroptosis activates platelets by increasing P-selectin, thus causing thromboembolism. Ferroptosis mediates virus infection and parasite infection by driving T-cell death and preventing T-cell immunity. Interestingly, ferroptosis is also considered as a critical player in COVID-19 infections, while targetting ferroptosis may also improve thromboembolism and prognosis in patients with COVID-19 infection. Overall, the crucial role of ferroptosis in blood cells will show a new therapeutic potential in blood cell-related diseases.HighlightsFerroptosis shows a new therapeutic potential for blood cell-related diseases.Ferroptosis damages erythropoiesis and thus induces anaemia.Ferroptosis induces platelet activation and leads to thromboembolism.Ferroptosis regulates T-cell and B-cell immunity, which participant in infectious diseases.Inversely, ferroptosis ameliorates acute myeloid leukaemia and T-cell leukaemia.

Body weight and its influence on hepcidin levels in patients with type 2 diabetes: A systematic review and meta-analysis of clinical studies

INTRODUCTION

Iron profiles in patients with type 2 diabetes (T2D) are inconsistent. In this study, we assessed the levels of hepcidin, a regulatory protein involved in iron homoeostasis, in patients with T2D. We further evaluated the surrogate markers of hepcidin action, particularly those associated with erythropoiesis.

METHODS

This systematic review and meta-analysis was reported following the Meta-analysis Of Observational Studies in Epidemiology (MOOSE) guidelines. We searched for relevant studies in electronic databases from inception until 31 October 2020 without any language restriction. The random effects model was used to calculate effect estimates, and outcomes were reported as either standardised mean difference (SMD) or mean differences (MD), 95 percent confidence interval (95% CI).

RESULTS

Eleven studies involving 2 620 participants were included in this study. Patients with T2D had a slight increase in hepcidin levels when compared to controls SMD: 0.07 [95% CI: -0.30, 0.44]. The subgroup analysis showed that studies involving patients with T2D who were overweight reported elevated hepcidin levels SMD: 0.35 [95% CI: 0.07, 0.62] whilst those with grade I obesity described reduced levels SMD: -0.42 [95% CI: -1.21, 0.38]. All T2D patients had low levels of haemoglobin MD: -0.23 g/dl [95% CI: -0.46, -0.01] irrespective of body weight.

CONCLUSION

The levels of hepcidin are altered in patients with T2D and are disproportionately influenced by weight. Moreover, patients with T2D present with subclinical anaemia despite elevated iron stores. The regulation of hepcidin in patients with T2D is dependent on several factors and vary greatly, thus its sole use in clinical settings may be less beneficial.

Diabesity negatively affects transferrin saturation and iron status. The DICARIVA study

AIMS

The relationship between iron status, obesity and type 2 diabetes mellitus (T2DM) has scarcely been tested. This study hypothesizes that patients with obesity and T2DM have altered iron metabolism.

METHODS

537 T2DM patients were selected from the cross-sectional DICARIVA study excluding patients with high-sensitivity-C-reactive-protein (hs-CRP) ≥  10 mg/L. Three groups according to body mass index (BMI) and waist perimeter (WP) were analysed: a) BMI < 30 kg/m², non-high WP (n = 105); b) BMI < 30 kg/m², high WP (n = 202); and c) diabesity, BMI ≥  30 kg/m², high WP (n = 230). Group differences on cardiometabolic and iron status markers were tested.

RESULTS

Women had significantly lower iron, ferritin, and transferrin saturation (TSAT) but higher transferrin and total iron binding capacity than men. Triglycerides/HDL-c ratio, as insulin-resistance (IR) marker, was higher in men while hs-CRP in women. TSAT was inversely related to BMI and hs-CRP. The diabesity group showed the highest hs-CRP (p < 0.001) and IR (p < 0.001) with the lowest TSAT (p = 0.003).

CONCLUSIONS

Low TSAT was highly prevalent in diabesity, mainly in women, suggesting that IR, inflammation, and abdominal adiposity alter iron transport and accumulation. The convenience of iron supplementation in diabesity patients with low TSAT should be urgently assessed, due the pro-oxidant effects of excess iron.

Mild iron overload induces TRIP12-mediated degradation of YY1 to trigger hepatic inflammation

Increasing populations are found to bear mild hepatic iron overload (HIO) due to unhealthy lifestyles, metabolic diseases, etc., whether this mild but chronic HIO induces hepatic inflammation is unknown. In the present study, mice receiving a 12-months 0.3% dextran-iron diet show mild HIO with no detectable oxidative damages in the liver but have infiltrated macrophages and increased IL-6, TNFα, AST and ALT since 6-months. The HNF4α/miR-122/CCL2 pathway, identified by our previous studies to induce macrophages infiltration, is initiated by chronic mild HIO. After excluding the role of DNA methylation, a modified transcription factor microarray is applied to find that transcription factor YY1 is responsible for HIO-decreased HNF4α expression. Then the E3 ubiquitin ligase TRIP12 is identified by an immunoprecipitation coupled LC-MS/MS and proved to bind and ubiquitinate YY1, leading to its degradation. The overexpression or silence of YY1 in the liver regulates the HNF4α/miR-122/CCL2 pathway. More importantly, YY1 overexpression alleviates chronic mild HIO induced hepatic inflammatory responses. In conclusion, these results elucidate an oxidative-stress-independent, TRIP12/YY1/HNF4α/miR-122/CCL2 pathway of chronic mild HIO inducing hepatic inflammation, implying that effective measures in addition to antioxidants are needed for individuals at the risk of chronic mild HIO.

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.

Regulatory Connections between Iron and Glucose Metabolism

Iron is essential for energy metabolism, and states of iron deficiency or excess are detrimental for organisms and cells. Therefore, iron and carbohydrate metabolism are tightly regulated. Serum iron and glucose levels are subjected to hormonal regulation by hepcidin and insulin, respectively. Hepcidin is a liver-derived peptide hormone that inactivates the iron exporter ferroportin in target cells, thereby limiting iron efflux to the bloodstream. Insulin is a protein hormone secreted from pancreatic β-cells that stimulates glucose uptake and metabolism via insulin receptor signaling. There is increasing evidence that systemic, but also cellular iron and glucose metabolic pathways are interconnected. This review article presents relevant data derived primarily from mouse models and biochemical studies. In addition, it discusses iron and glucose metabolism in the context of human disease.

The effect of hepcidin on components of metabolic syndrome in chronic kidney disease: a cross-sectional study

BACKGROUND

Hepcidin is an important regulator of iron homeostasis.

OBJECTIVES

This cross-sectional study was conducted to evaluate the association between hepcidin and components of metabolic syndrome in patients with chronic kidney disease (CKD).

DESIGN AND SETTING

103 CKD patients and 59 healthy volunteers were included in the study from the University Hospital.

METHODS

Serum hepcidin levels were measured by enyzme-linked immunosorbent assay (ELISA) test. As for the study parameters, age, sex, body mass index, renal diseases, serum biochemistry, complete blood count, iron and total iron-binding capacity, ferritin, high-sensitive C-reactive protein (hsCRP), C- reactive protein (CRP), and erythrocyte sedimentation rate (ESR) were evaluated.

RESULTS

The mean age of the patients was 58.63 ± 11.8 years. Hepcidin level was significantly associated with hypertension and higher uric acid levels (P < 0.05). There was a positive correlation between hepcidin and urea, uric acid, creatinine, ferritin, CRP, ESR, phosphorus, triglyceride, low-density lipoprotein (LDL), proteinuria and albuminuria in 24-hour urine collection. A negative correlation was found between hepcidin and estimated glomerular filtration rate (eGFR), hemoglobin, hematocrit, calcium, 25 OH vitamin D, pH, and bicarbonate levels.

CONCLUSION

Hepcidin, a well-known hormone regulator of iron metabolism, may play an important role in the pathogenesis of metabolic syndrome in patients with CKD, and further studies might delineate in-depth its potential as a promising early marker in these patients.

Iron overload and Hepcidin overexpression could play a key role in COVID infection, and may explain vulnerability in elderly, diabetics, and obese patients

BACKGROUND

The COVID epidemic hit like a tsunami worldwide. At the time of its arrival in Italy, available literary data were meager, and most of them concerned its epidemiology. World Health Organization proposed guidelines in march 2020, a strategy of treatment has been developed, and a significant number of subsequent articles have been published to understand, prevent, and cure COVID patients.

METHODS

From the observation of two patients, we performed a careful analysis of scientific literature to unearth the relation between COVID infection, clinical manifestations as pneumonia and thrombosis, and to find out why it frequently affects obese, diabetics, and elderly patients.

RESULTS

The analysis shows that hepcidin could represent one of such correlating factors. Hepcidin is most elevated in older age, in non-insulin diabetics patients and in obese people. It is the final target therapy of many medicaments frequently used. Viral disease, and in particular SARS-CoV19, could induce activation of the hepcidin pathway, which in turn is responsible for an increase in the iron load. Excess of iron can lead to cell death by ferroptosis and release into the bloodstream, such as free iron, which in turn has toxic and pro-coagulative effects.

CONCLUSIONS

Overexpression of hepcidin and iron overload might play a crucial role in COVID infection, becoming potential targets for treatment. Hepcidin could also be considered as a biomarker to measure the effectiveness of our treatments and the restoration of iron homeostasis the final intent. (www.actabiomedica.it).

Iron metabolism and type 2 diabetes mellitus: A meta-analysis and systematic review

AIMS/INTRODUCTION

Iron metabolism can directly or indirectly affect the occurrence and development of type 2 diabetes. This meta-analysis and systematic review aimed to analyze the association between serum iron metabolism indicators and type 2 diabetes.

MATERIALS AND METHODS

The databases PubMed and Embase were searched for studies on the correlations between serum iron metabolism indicators (iron, ferritin, transferrin, hepcidin and soluble transferrin receptor) and type 2 diabetes since January 2006. Relevant data were extracted from the included studies, and meta-analysis was carried out.

RESULTS

A total of 12 case-control and cohort studies were analyzed. Of the 12 studies, 11 described the correlation between serum ferritin levels and type 2 diabetes. The median and high serum ferritin concentrations were significantly associated with the risks of type 2 diabetes (odds ratio [OR] 1.20, 95% confidence interval [CI] 1.08-1.33 and OR 1.43, 95% CI 1.29-1.59, respectively). However, the low concentration was not correlated with the risk of type 2 diabetes (OR 0.99, 95% CI 0.89-1.11). No significant association was observed between serum soluble transferrin receptor and type 2 diabetes, whereas the soluble transferrin receptor-to-ferritin ratio was significantly inversely related to the risk of type 2 diabetes in the median and high ratio subgroups (OR 0.71, 95% CI 0.51, 0.99 and OR 0.65, 95% CI 0.45-0.95).

CONCLUSIONS

The elevated serum ferritin was one of the risk factors for type 2 diabetes, and soluble transferrin receptor-to-ferritin ratio was inversely related to the risk of type 2 diabetes. A systematic review showed that serum transferrin and hepcidin might be directly or indirectly related to the development of diabetes.

Comprehensive Glycomic Analysis Reveals That Human Serum Albumin Glycation Specifically Affects the Pharmacokinetics and Efficacy of Different Anticoagulant Drugs in Diabetes

Long-term hyperglycemia in patients with diabetes leads to human serum albumin (HSA) glycation, which may impair HSA function as a transport protein and affect the therapeutic efficacy of anticoagulants in patients with diabetes. In this study, a novel mass spectrometry approach was developed to reveal the differences in the profiles of HSA glycation sites between patients with diabetes and healthy subjects. K199 was the glycation site most significantly changed in patients with diabetes, contributing to different interactions of glycated HSA and normal HSA with two types of anticoagulant drugs, heparin and warfarin. An in vitro experiment showed that the binding affinity to warfarin became stronger when HSA was glycated, while HSA binding to heparin was not significantly influenced by glycation. A pharmacokinetic study showed a decreased level of free warfarin in the plasma of diabetic rats. A preliminary retrospective clinical study also revealed that there was a statistically significant difference in the anticoagulant efficacy between patients with diabetes and patients without diabetes who had been treated with warfarin. Our work suggests that larger studies are needed to provide additional specific guidance for patients with diabetes when they are administered anticoagulant drugs or drugs for treating other chronic diseases.

Effects of fasting on liver glycogen structure in rats with type 2 diabetes

Liver glycogen, a highly branched glucose polymer, is important for blood sugar homeostasis. It comprises α particles which are made of linked β particles; the molecular structure changes diurnally. In diabetic liver, the α particles are fragile, easily breaking apart into β particles in chaotropic agents such as dimethyl sulfoxide. We here use size-exclusion chromatography to study how fasting changes liver-glycogen structure in vivo for mice in which type-2 diabetes had previously been induced. Diabetic glycogen degraded enzymatically more quickly in the fasted animals than did glycogen without fasting, with fewer α particles, which however were still fragile. The glycogen had fewer long chains and more shorter chains after fasting. This study gives an overview of the in vivo dynamic changes in α-particles under starvation conditions in both normal and diabetic livers.

BCc1 Nanomedicine Therapeutic Effects in Streptozotocin and High-Fat Diet Induced Diabetic Kidney Disease

BACKGROUND

One common feature of chronic diseases, such as cancer, diabetes and chronic kidney disease (CKD), is the disruption of iron metabolism and increase in labile iron pool, which can result in excessive production of harmful oxidative stress. The proper management of iron metabolism in this situation can be a valuable tool to ameliorate pathological events.

MATERIALS AND METHODS

In the previous studies, the anti-neoplastic effects of BCc1, a nanochelating-based nanomedicine with iron-chelating property, were demonstrated in cell culture, animal models and clinical trials. In the present study, the therapeutic effects of BCc1 in animal model of diabetic kidney disease (DKD), induced by streptozotocin injection (35 mg/kg) and high-fat diet consumption, were evaluated.

RESULTS

The results showed that BCc1 significantly decreased HOMA-IR index, uric acid, blood urea nitrogen, malondialdehyde and 8-isoprostane. In addition, it reduced urinary albumin excretion rate and albumin-to-creatinine ratio in comparison to DKD control rats. This nanomedicine had no negative impact on liver iron content, hemoglobin level, red blood cell count, hematocrit and mean corpuscular volume, while it significantly decreased aspartate aminotransferase and alanine aminotransferase compared to DKD control group. Moreover, the histopathological assessment indicated that lesser glomerular basement membrane and wrinkling, mesangial matrix expansion and pathological changes in proximal cortical tubules were seen in the kidney samples of BCc1-treated rats.

CONCLUSION

In conclusion, BCc1 as an iron-chelating agent shows promising impacts in DKD animal model, which can ameliorate biochemical and pathological events of this disease.

The freeze-dried extracts of Rotheca myricoides (Hochst.) Steane & Mabb possess hypoglycemic, hypolipidemic and hypoinsulinemic on type 2 diabetes rat model

ETHNOPHARMACOLOGICAL RELEVANCE

Rotheca myricoides (Hochst.) Steane & Mabb is a plant species used in traditional medicine for the management of diabetes in the lower eastern part of Kenya (Kitui, Machakos and Makueni Counties, Kenya) that is mainly inhabited by the Kamba community.

AIM

This study investigated the antihyperglycaemic, antidyslipidemic and antihyperinsulinemic activity of the freeze-dried extracts of Rotheca myricoides (Hochst.) Steane & Mabb (RME) in an animal model of type 2 diabetes mellitus.

METHODS

Type 2 diabetes was induced by dietary manipulation for 56 days via (high fat- high fructose diet) and intraperitoneal administration of streptozocin (30 mg/kg). Forty freshly-weaned Sprague Dawley rats were randomly assigned into the negative control (high fat/high fructose diet), low dose test (50mg/kg RME, high dose test (100mg/kg RME and positive control (Pioglitazone, 20mg/kg) groups. Fasting blood glucose and body weight were measured at weekly intervals. Oral glucose tolerance tests were performed on days 28 and 56. Lipid profile, hepatic triglycerides, fasting serum insulin levels and serum uric acid were determined on day 56.

RESULTS

The RME possessed significant antihyperglycemic [FBG: 6.5 ± 0.11 mmol/l (negative control) vs. 4.62 ± 0.13 mmol/l (low dose test) vs. 5.25 ± 0.15 mmol/l in (high dose test) vs. 4.33 ± 0.09 mmol/l (positive control): p < 0.0001] and antihyperinsulinemic effects [1.84 ± 0.19 (negative control) vs. (0.69 ± 0.13 (low dose test) vs. (0.83 ± 0.17 (high dose test) vs. (0.69 ± 0.10 (positive control): F (3, 36) = 0.6421: p < 0.0001. The extracts also possessed significant antidyslipidemic effects [LDL levels: 3.52 ± 0.19 mmol/l (negative control) vs. 0.33 ± 0.14 mmol/l (low dose test) vs. 0.34 ± 0.20 mmol/l (high dose test) vs. 0.33 ± 0.01 mmol/l (positive control): p < 0.0001].RME significantly lowered plasma uric acid levels, as well as hepatic triglycerides and hepatic weights. Network pharmacology analysis indicated that the observed pharmacological effects are mediated via the modulation of Peroxisome proliferator-activated gamma receptor.

CONCLUSIONS

The freeze dried extracts of Rotheca myricoides possessed significant antihyperglycemic and antidyslidemic effects. In addition it lowered serum uric levels, as well as hepatic triglycerides and hepatic weight. These results appear to validate the traditional use of this plant species in the management of diabetes mellitus.

Serum ferritin as a candidate diagnostic biomarker of polycystic ovarian syndrome: a meta-analysis

Objective: In this study, we investigated about the potential of serum ferritin as a complementary diagnostic biomarker of polycystic ovarian syndrome (PCOS) by performing a meta-analysis of existing literature. Materials and methods: Eleven studies written in English were retrieved up to 30 June 2018. Data were extracted from the selected studies by two of the authors and was subjected to statistical analysis. Levels of serum ferritin were compared between women with PCOS and controls using the standardized mean difference (SMD) and 95% confidence interval (CI). Subgroup analysis was also performed and stratified by ethnicity (Asians versus Caucasians). Results: Overall post-outlier outcomes indicated that elevated serum ferritin is strongly associated with PCOS (SMD: 0.52; 95% CI: 0.40-0.64; P^A = 10^-5). Subgroup analysis by ethnicity showed no significant difference between Asian and Caucasian population. Post-outlier receiving operations characteristics curve were plotted and showed that values for serum ferritin showed good potential in discriminating patients with and without PCOS (AUC = 0.827, p = 0.006). Conclusion: Our findings suggest that high serum ferritin level is significantly associated with PCOS and its potential as a biomarker is evident in its high diagnostic accuracy. However, additional studies are needed to confirm our claims.

Iron Metabolism, Hepcidin, and Mortality (the Ludwigshafen Risk and Cardiovascular Health Study)

BACKGROUND

Anemia has been shown to be a risk factor for coronary artery disease (CAD) and mortality, whereas the role of iron metabolism remains controversial.

METHODS

We analyzed iron metabolism and its associations with cardiovascular death and total mortality in patients undergoing coronary angiography with a median follow-up of 9.9 years. Hemoglobin and iron status were determined in 1480 patients with stable CAD and in 682 individuals in whom significant CAD had been excluded by angiography.

RESULTS

Multivariate-adjusted hazard ratios (HRs) for total mortality in the lowest quartiles of iron, transferrin saturation, ferritin, soluble transferrin receptor (sTfR), and hemoglobin were 1.22 (95% CI, 0.96-1.60), 1.23 (95% CI, 0.97-1.56), 1.27 (95% CI, 1.02-1.58), 1.26 (95% CI, 0.97-1.65), and 0.99 (95% CI, 0.79-1.24), respectively, compared to the second or third quartile, which served as reference (1.00) because of a J-shaped association. The corresponding HRs for total mortality in the highest quartiles were 1.44 (95% CI, 1.10-1.87), 1.37 (95% CI, 1.05-1.77), 1.17 (95% CI, 0.92-1.50), 1.76 (95% CI, 1.39-2.22), and 0.83 (95% CI, 0.63-1.09). HRs for cardiovascular death were similar. For hepcidin, the adjusted HRs for total mortality and cardiovascular deaths were 0.62 (95% CI, 0.49-0.78) and 0.70 (95% CI, 0.52-0.90) in the highest quartile compared to the lowest one.

CONCLUSIONS

In stable patients undergoing angiography, serum iron, transferrin saturation, sTfR, and ferritin had J-shaped associations and hemoglobin only a marginal association with cardiovascular and total mortality. Hepcidin was continuously and inversely related to mortality.

Reduction of hemoglobin, not iron, inhibited maturation of red blood cells in male rats exposed to high intensity endurance exercises

The existence of sports anemia, induced by strenuous or long-term exercise and characterized by decreases of red blood cells (RBCs), hemoglobin and iron content, remains to be doubtful. To observe the effects of endurance exercise on RBCs and explain the underlying reason, we designed this study by observing RBCs parameters and iron metabolism in 8-weeks training rats and effects of iron supplement or protein supplement on RBCs. Results showed that erythrocyte counts, hematocrit, mean corpuscular volume and hemoglobin content decreased while RBC distribution width increased in exercised rats at later stage during 8 weeks training. But the contents of serum iron and ferritin decreased only at 1-week and 2-week and returned to normal at 4-week and 8-week. Same as iron content, apparent iron absorption rate was declined at early stage but restored to normal level at 8-week, as well as serum adrenaline, cortisol and insulin levels. Instead, the contents of total protein and albumin in serum were decreased at later stage during 8-weeks training. Furthermore, we observed that protein supplement ameliorated RBCs parameters in rats exposed to 8 weeks swimming exercise, but iron supplement had no effects on RBCs, though it obviously increased iron content of serum and the liver. Based on these results, we drew a conclusion that transient changes of iron metabolism, which may be induced by stress hormone changes, was not the reason for RBCs decrease in endurance exercises but hemoglobin reduction, induced by defects in protein supplement, impeded development of RBCs.

Hyperglycemia promotes microvillus membrane expression of DMT1 in intestinal epithelial cells in a PKCα-dependent manner

Excessive iron increases the incidence of diabetes and worsens diabetic complications. Reciprocally, diabetes induces iron loading, partially attributable to elevated intestinal iron export according to a recent report. Herein, we show that iron uptake and the mRNA expression of iron importer divalent metal transporter 1 (DMT1) were significantly increased in the duodenum of streptozotocin-induced diabetic mice. Immunofluorescence staining of human intestinal biopsies revealed increased brush border membrane (BBM) and decreased cytoplasmic DMT1 expression in patients with diabetes, suggesting translocation of DMT1. This pattern of DMT1 regulation was corroborated by immunoblotting results in diabetic mice showing that BBM DMT1 expression was increased by 210%, in contrast to a 60% increase in total DMT1. PKC mediates many diabetic complications, and PKCα activity was increased in diabetic mouse intestine. Intriguingly, diabetic mice with PKCα deficiency did not show increases in iron uptake and BBM DMT1 expression. High-glucose treatment increased plasma membrane DMT1 expression via the activation of PKCα in cultured IECs. Inhibition of PKCα potentiated the ubiquitination and degradation of DMT1 protein. We further showed that high glucose suppressed membrane DMT1 internalization. These findings demonstrate that PKCα promotes microvillus membrane DMT1 expression and intestinal iron uptake, contributing to diabetic iron loading.-Zhao, L., Bartnikas, T., Chu, X., Klein, J., Yun, C., Srinivasan, S., He, P. Hyperglycemia promotes microvillus membrane expression of DMT1 in intestinal epithelial cells in a PKCα-dependent manner.

Insulin receptor signaling regulates renal collecting duct and intercalated cell antibacterial defenses

People with diabetes mellitus have increased infection risk. With diabetes, urinary tract infection (UTI) is more common and has worse outcomes. Here, we investigate how diabetes and insulin resistance impact the kidney's innate defenses and urine sterility. We report that type 2 diabetic mice have increased UTI risk. Moreover, insulin-resistant prediabetic mice have increased UTI susceptibility, independent of hyperglycemia or glucosuria. To identify how insulin resistance affects renal antimicrobial defenses, we genetically deleted the insulin receptor in the kidney's collecting tubules and intercalated cells. Intercalated cells, located within collecting tubules, contribute to epithelial defenses by acidifying the urine and secreting antimicrobial peptides (AMPs) into the urinary stream. Collecting duct and intercalated cell-specific insulin receptor deletion did not impact urine acidification, suppressed downstream insulin-mediated targets and AMP expression, and increased UTI susceptibility. Specifically, insulin receptor-mediated signaling regulates AMPs, including lipocalin 2 and ribonuclease 4, via phosphatidylinositol-3-kinase signaling. These data suggest that insulin signaling plays a critical role in renal antibacterial defenses.

Protective Role of Histidine Supplementation Against Oxidative Stress Damage in the Management of Anemia of Chronic Kidney Disease

Anemia is a major health condition associated with chronic kidney disease (CKD). A key underlying cause of this disorder is iron deficiency. Although intravenous iron treatment can be beneficial in correcting CKD-associated anemia, surplus iron can be detrimental and cause complications. Excessive generation of reactive oxygen species (ROS), particularly by mitochondria, leads to tissue oxidation and damage to DNA, proteins, and lipids. Oxidative stress increase in CKD has been further implicated in the pathogenesis of vascular calcification. Iron supplementation leads to the availability of excess free iron that is toxic and generates ROS that is linked, in turn, to inflammation, endothelial dysfunction, and cardiovascular disease. Histidine is indispensable to uremic patients because of the tendency toward negative plasma histidine levels. Histidine-deficient diets predispose healthy subjects to anemia and accentuate anemia in chronic uremic patients. Histidine is essential in globin synthesis and erythropoiesis and has also been implicated in the enhancement of iron absorption from human diets. Studies have found that L-histidine exhibits antioxidant capabilities, such as scavenging free radicals and chelating divalent metal ions, hence the advocacy for its use in improving oxidative stress in CKD. The current review advances and discusses evidence for iron-induced toxicity in CKD and the mechanisms by which histidine exerts cytoprotective functions.

Ironing out the Details: Untangling Dietary Iron and Genetic Background in Diabetes

The search for genetic risk factors in type-II diabetes has been hindered by a failure to consider dietary variables. Dietary nutrients impact metabolic disease risk and severity and are essential to maintaining metabolic health. Genetic variation between individuals confers differences in metabolism, which directly impacts response to diet. Most studies attempting to identify genetic risk factors in disease fail to incorporate dietary components, and thus are ill-equipped to capture the breadth of the genome's impact on metabolism. Understanding how genetic background interacts with nutrients holds the key to predicting and preventing metabolic diseases through the implementation of personalized nutrition. Dysregulation of iron homeostasis is associated with type-II diabetes, but the link between dietary iron and metabolic dysfunction is poorly defined. High iron burden in adipose tissue induces insulin resistance, but the mechanisms underlying adipose iron accumulation remain unknown. Hepcidin controls dietary iron absorption and distribution in metabolic tissues, but it is unknown whether genetic variation influencing hepcidin expression modifies susceptibility to dietary iron-induced insulin resistance. This review highlights discoveries concerning the axis of iron homeostasis and adipose function and suggests that genetic variation underlying dietary iron metabolism is an understudied component of metabolic disease.