Glucose dysregulation in patients with iron overload: is there a relationship with quantitative pancreas and liver iron and fat content measured by MRI?

Quantitative Magnetic Resonance Imaging for the Pancreas: Current Status

ABSTRACT

Magnetic resonance imaging (MRI) is important for evaluating pancreatic disorders, and anatomical landmarks play a major role in the interpretation of results. Quantitative MRI is an effective diagnostic modality for various pathologic conditions, as it allows the investigation of various physical parameters. Recent advancements in quantitative MRI techniques have significantly improved the accuracy of pancreatic MRI. Consequently, this method has become an essential tool for the diagnosis, treatment, and monitoring of pancreatic diseases. This comprehensive review article presents the currently available evidence on the clinical utility of quantitative MRI of the pancreas.

High Dietary Iron in Western Diet-Fed Male Rats Causes Pancreatic Islet Injury and Acute Pancreatitis

BACKGROUND

High dietary iron has been linked to an increased type 2 diabetes risk. We have previously shown that intrauterine growth restriction (IUGR) and feeding a Western diet (WD) to male Sprague-Dawley rats independently, as well as together, cause pancreatic islet inflammation, fibrosis, and hemosiderosis.

OBJECTIVES

To investigate whether iron has a role in the pathogenesis of this inflammatory islet injury caused by IUGR and WD intake.

METHODS

Male Sprague-Dawley offspring of bilateral uterine artery ligated (IUGR) and sham-operated (Sham) dams, fostered to nonoperated dams, were fed a WD [45% sucrose, 19.4% protein and 23% fat (w/w)] containing low iron (LI, 20 mg/kg) or high iron (HI, 500 mg/kg) from weaning. Four groups were studied: Sham-LI, Sham-HI, IUGR-LI, and IUGR-HI. Serial measurements of rat body weight, blood glucose, lipids and insulin, an intraperitoneal glucose tolerance test (age 13 wk), and histological analysis of pancreas and liver (age 14 wk) were recorded. The effects of iron, IUGR, and their interaction, on these measurements have been analyzed.

RESULTS

WD with HI compared with LI caused an 11% greater weight gain by age 14 wk (P < 0.001), impaired glucose tolerance [AUC for glucose (G-AUC) 17% higher; P < 0.001), acute pancreatitis (17/18, HI; 6/17, LI; P < 0.001), pancreas-associated fat necrosis and saponification (7/18, HI; 0/17 LI; P < 0.01), and a trend to islet fibrotic injury (7/18, HI; 1/17 LI; P = 0.051). Although pancreatic and hepatic steatosis was evident in almost all WD-fed rats, pancreatic and hepatic iron accumulation was prevalent only in HI-fed rats (P < 0.0001 for both), being only mild in the livers. IUGR, independent of dietary iron, also caused impairment in glucose tolerance (G-AUC: 17% higher; P < 0.05).

CONCLUSIONS

A postweaning WD containing HI, independent of IUGR, causes acute pancreatitis and islet injury in Sprague-Dawley rats suggesting a role of dietary iron in the development of steatopancreatitis.

Association of hepatic/pancreatic iron overload evaluated by quantitative T2* MRI with bone mineral density and trabecular bone score

BACKGROUND

Iron-overloaded patients are recognized as presenting an increased risk of osteoporosis. However, studies on the correlation between osteoporosis and organ iron overload are controversial or scarce. The aim of this study is to assess bone mineral density (BMD) and trabecular bone score (TBS) in correlation with hepatic and pancreatic iron overload.

METHODS

Forty-one patients diagnosed with hemoglobinopathies, were studied. BMDs of the lumbar spine (LS), femoral neck (FN), and total hip (TH) were analyzed by Dual-energy X-ray absorptiometry (DXA) scan. LS bone quality was derived from each spine DXA examination using the TBS analysis. Hepatic and pancreatic iron overload were obtained with a multi-echo gradient echo T2* technique.

RESULTS

Abnormal microarchitecture and abnormal bone mass were observed in 19/41 (46.3%) and 9/41 (22.0%) patients, respectively. For 26 males, BMD, T-score and Z-score of LS were significantly lower among subjects with moderate-severe hepatic iron-overload than their counterparts, as it is between no- and pancreatic iron-overload groups. For 15 females, patients with moderate-severe hepatic iron-overload had significantly lower BMD and T-score of FN and TH, and patients with pancreatic iron-overload had significantly lower BMD, T-score of FN, and lower BMD, T-score and Z-score of TH than their counterparts. Moreover, pancreatic T2*-value was positively correlated with BMD and T-score at all analyzed sites and Z-score at TH.

CONCLUSION

These data showed lower bone mass in patients with organ iron overload, particularly for LS in males, FN and TH in females. TBS may well represent a complementary tool for the evaluation of bone quality and the risk of fracture in iron-overloaded patients.

Fatty Pancreas-Centered Metabolic Basis of Pancreatic Adenocarcinoma: From Obesity, Diabetes and Pancreatitis to Oncogenesis

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest types of cancer, and it is currently the third most common cause of cancer death in the U.S.A. Progress in the fight against PDAC has been hampered by an inability to detect it early in the overwhelming majority of patients, and also by the reduced oxygen levels and nutrient perfusion caused by new matrix formation through the activation of stromal cells in the context of desmoplasia. One harbinger of PDAC is excess intrapancreatic fat deposition, namely, fatty pancreas, which specifically affects the tumor macro- and microenvironment in the organ. Over half of PDAC patients have diabetes mellitus (DM) at the time of diagnosis, and fatty pancreas is associated with subsequent DM development. Moreover, there is a strong association between fatty pancreas and fatty liver through obesity, and a higher intrapancreatic fat percentage has been noted in acute pancreatitis patients with DM than in those without DM. All these findings suggest that the link between fatty pancreas and PDAC might occur through metabolic alterations, either DM-related or non-DM-related. Based on clinical, in vivo and in vitro evidence, the current review highlights the etiologies of fatty pancreas (including fatty infiltration and replacement) and the fatty pancreas-associated metabolic alterations involved in oncogenesis to provide crucial targets to prevent, detect, and/or effectively treat PDAC.

Iodine excess induces hepatic, renal and pancreatic injury in female mice as determined by attenuated total reflection Fourier-transform infrared spectrometry

Limited knowledge of the long-term effects of excessive iodine (EI) intake on biomolecular signatures in the liver/pancreas/kidney prompted this study. Herein, following 6 months of exposure in mice to 300, 600, 1200 or 2400 μg/L iodine, the biochemical signature of alterations to the liver/pancreas/kidney was profiled using attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy coupled with principal component analysis-linear discriminant analysis (PCA-LDA). Our research showed that serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (BUN), serum creatinine (Scr), insulin, blood glucose levels and homeostasis model assessment for insulin resistance (HOMA-IR) index in the 1200 and 2400 μg/L iodine-treated groups were significantly increased compared with those in the control group. Moreover, histological analysis showed that the liver/kidney/pancreas tissues of mice exposed to EI treatment displayed substantial morphological abnormalities, such as a loss of hepatic architecture, glomerular cell vacuolation and pancreatic neutrophilic infiltration. Notably, EI treatment caused distinct biochemical signature segregation between EI-exposed versus the control liver/pancreas/kidney. The main biochemical alterations between EI-exposed and control groups were observed for protein phosphorylation, protein secondary structures and lipids. The ratios of amide I-to-amide II (1674 cm^-1 /1570 cm^-1 ), α-helix-to-β-sheet (1657 cm^-1 /1635 cm^-1 ), glycogen-to-phosphate (1030 cm^-1 /1086 cm^-1 ) and the peptide aggregation (1 630 cm^-1 /1650 cm^-1 ) level of EI-treated groups significantly differed from the control group. Our study demonstrated that EI induced hepatic, renal and pancreatic injury by disturbing the structure, metabolism and function of the cell membrane. This finding provides the new method and implication for human health assessment regarding long-term EI intake.

Ferroptosis and Its Potential Role in Metabolic Diseases: A Curse or Revitalization?

Ferroptosis is classified as an iron-dependent form of regulated cell death (RCD) attributed to the accumulation of lipid hydroperoxides and redox imbalance. In recent years, accumulating researches have suggested that ferroptosis may play a vital role in the development of diverse metabolic diseases, for example, diabetes and its complications (e.g., diabetic nephropathy, diabetic cardiomyopathy, diabetic myocardial ischemia/reperfusion injury and atherosclerosis [AS]), metabolic bone disease and adrenal injury. However, the specific physiopathological mechanism and precise therapeutic effect is still not clear. In this review, we summarized recent advances about the development of ferroptosis, focused on its potential character as the therapeutic target in metabolic diseases, and put forward our insights on this topic, largely to offer some help to forecast further directions.

Quantification of pancreatic iron overload and fat infiltration and their correlation with glucose disturbance in pediatric thalassemia major patients

Background

Diabetes mellitus affects more than a quarter of patients with thalassemia major (TM) worldwide, and increases the risk for cardiac complications, contributing to significant morbidity. Pancreatic iron overload (IO) and fat infiltration have been correlated with this endocrinal complication in adult TM patients. It has been shown that in adult TM patients, iron accumulation and fat infiltration are found to be heterogeneous in the pancreatic head, body, and tail region. R2* and a fat fraction (FF) generated by gradient-echo imaging can be used as quantitative parameters to assess the iron and fat contents of the pancreas. This study aimed to determine the pattern of pancreatic iron accumulation and fat infiltration in pediatric TM patients with gradient-echo imaging and evaluate the association between pancreatic IO and fat infiltration and glucose disturbances.

Methods

A total of 90 children with TM (10.7±3.1 years) were included. All patients underwent pancreatic magnetic resonance imaging (MRI) using multi-echo gradient-echo sequences. IO was measured by R2* relaxometry in 90 patients, and FF values were measured using iterative decomposition of water and fat with echo asymmetry and the least-squares estimation (IDEAL) method in 40 patients. R2* and FF were assessed in the pancreatic head, body, and tail. The global R2* and global FF values were obtained by averaging the respective values from the pancreatic head, body, and tail. The correlations between global R2*, global FF, and fasting glucose were determined using Spearman's correlation analysis. The Friedman test was used to compare R2* and FF among different pancreatic regions. Receiver operating characteristic (ROC) analysis was used to determine the performance of global R2* and global FF in discriminating impaired fasting glucose from normal fasting glucose patients.

Results

The global R2* was positively correlated with the global FF in the pancreas (r=0.895, P<0.001). No significant differences were found in R2* among the 3 regions of the pancreas (χ²=4.050, P=0.132), but significant differences were found in FF among the 3 pancreatic regions (χ²=16.350, P<0.001). Both global pancreatic R2* (r=0.408, P<0.001) and global FF (r=0.523, P=0.001) were positively correlated with fasting glucose. ROC analysis showed that global pancreatic R2* and global FF had an area under the curve of 0.769 and 0.931 (both P<0.001), respectively, in discriminating between impaired and normal glucose function patients.

Conclusions

Pediatric TM patients can have homogeneous iron siderosis and heterogeneous fat infiltration in the pancreas as measured by gradient-echo imaging, both of which are risk factors for 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.