Tissue iron quantification in chronic liver diseases using MRI shows a relationship between iron accumulation in liver, spleen, and bone marrow

Bajitianwan formula extract ameliorates bone loss induced by iron overload via activating RAGE/PI3K/AKT pathway based on network pharmacology and transcriptomic analysis

Osteoporosis (OP) is closely related to iron overload. Bajitianwan (BJTW) is a traditional Chinese medicine formulation used for treating senile diseases such as dementia and osteoporosis. Modern pharmacological researches have found that BJTW has beneficial effect on bone loss and memory impairment in aging rats. This paper aimed to explore the role and mechanism of BJTW in ameliorating iron overload-induced bone loss. Furthermore, BJTW effectively improved the bone micro-structure of the femur in mice, and altered bone metabolism biomarkers alkaline phosphatase (ALP) and osteocalcin (OCN) in serum, as well as oxidative indexes superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR) glutathione (GSH) and malondialdehyde (MDA) in liver. As for network pharmacology, 73 components collected from BJTW regulated 99 common targets merged in the BJTW and OP. The results of RNA-seq indicated that there were 418 potential targets in BJTW low dose group (BJTW-L) and 347 potential targets in BJTW high dose group (BJTW-H). Intriguingly, both PI3K-AKT signaling pathway and the AGEs-RAGE signaling pathway were contained in the KEGG pathways enrichment results of network pharmacology and transcriptomics, which were considered as the potential mechanism. Additionally, we verified that BJTW regulated the expression of related proteins in RAGE/PI3K-AKT pathways in MC3T3-E1 cells. In summary, BJTW has potent effect on protecting against iron overload-induced OP, and its mechanism may be related to the activation of the RAGE/PI3K-AKT signaling pathways.

Survival analysis of patients with extrahepatic cholangiocarcinoma: a nomogram for clinical and MRI features

BACKGROUND

This study aimed to establish a predictive model to estimate the postoperative prognosis of patients with extrahepatic cholangiocarcinoma (ECC) based on preoperative clinical and MRI features.

METHODS

A total of 104 patients with ECC confirmed by surgery and pathology were enrolled from January 2013 to July 2021, whose preoperative clinical, laboratory, and MRI data were retrospectively collected and examined, and the effects of clinical and imaging characteristics on overall survival (OS) were analyzed by constructing Cox proportional hazard regression models. A nomogram was constructed to predict OS, and calibration curves and time-dependent receiver operating characteristic (ROC) curves were employed to assess OS accuracy.

RESULTS

Multivariate regression analyses revealed that gender, DBIL, ALT, GGT, tumor size, lesion's position, the signal intensity ratio of liver to paraspinal muscle (SIRLiver/Muscle), and the signal intensity ratio of spleen to paraspinal muscle (SIRSpleen/Muscle) on T2WI sequences were significantly associated with OS, and these variables were included in a nomogram. The concordance index of nomogram for predicting OS was 0.766, and the AUC values of the nomogram predicting 1-year and 2-year OS rates were 0.838 and 0.863, respectively. The calibration curve demonstrated good agreement between predicted and observed OS. 5-fold and 10-fold cross-validation show good stability of nomogram predictions.

CONCLUSIONS

Our nomogram based on clinical, laboratory, and MRI features well predicted OS of ECC patients, and could be considered as a convenient and personalized prediction tool for clinicians to make decisions.

Relationship between bone marrow iron load and liver iron concentration in dialysis-associated haemosiderosis

BACKGROUND

Iron overload due to the excessive use of parenteral iron in haemodialysis is now an increasingly recognised clinical issue. Before erythropoiesis-stimulating agents (ESA) were introduced, a specific feature of patients treated by dialysis and having iron overload was that iron levels in the bone marrow were paradoxically low in most of them, despite severe hepatosplenic siderosis. Whether or not this paradox persists in the actual ESA era was unknown until recently, when an autopsy study in 21 patients treated by haemodialysis revealed similarities between liver and bone marrow iron content. The aim of this study was to further explore these recent findings in a cohort of alive patients on dialysis and to analyse the determinants of iron bone marrow.

METHODS

Liver iron concentration (LIC) and vertebral T2∗ (a surrogate marker of bone marrow iron) were analysed retrospectively in 152 alive patients on dialysis (38.8% female) of whom 47.4% had iron overload by quantitative magnetic resonance imaging (MRI).

FINDINGS

Vertebral T2∗ differed significantly between patients classified according to liver iron content at MRI: those with mild or moderate and severe liver iron overload had increased vertebral iron content at R2∗ relaxometry MRI (mild: vertebral T2∗ = 9.9 ms (4-24.8); moderate and severe: vertebral T2∗ = 8.5 ms (4.9-22.8)) when compared to patients with normal LIC (vertebral T2∗ = 13.2 ms (6.6-30.5) (p < 0.0001 Kruskal-Wallis test)).

INTERPRETATION

The paradoxical discrepancy between bone marrow and liver iron-storage compartments observed in the pre-ESA era has disappeared today, as shown by a recent autopsy study and the present study in a cohort of alive patients treated by dialysis.

FUNDING

None.

Pancreatic steatosis and iron overload increases cardiovascular risk in non-alcoholic fatty liver disease

Objective

To assess the prevalence of pancreatic steatosis and iron overload in non-alcoholic fatty liver disease (NAFLD) and their correlation with liver histology severity and the risk of cardiometabolic diseases.

Method

A prospective, multicenter study including NAFLD patients with biopsy and paired Magnetic Resonance Imaging (MRI) was performed. Liver biopsies were evaluated according to NASH Clinical Research Network, hepatic iron storages were scored, and digital pathology quantified the tissue proportionate areas of fat and iron. MRI-biomarkers of fat fraction (PDFF) and iron accumulation (R2*) were obtained from the liver and pancreas. Different metabolic traits were evaluated, cardiovascular disease (CVD) risk was estimated with the atherosclerotic CVD score, and the severity of iron metabolism alteration was determined by grading metabolic hiperferritinemia (MHF). Associations between CVD, histology and MRI were investigated.

Results

In total, 324 patients were included. MRI-determined pancreatic iron overload and moderate-to severe steatosis were present in 45% and 25%, respectively. Liver and pancreatic MRI-biomarkers showed a weak correlation (r=0.32 for PDFF, r=0.17 for R2*). Pancreatic PDFF increased with hepatic histologic steatosis grades and NASH diagnosis (p<0.001). Prevalence of pancreatic steatosis and iron overload increased with the number of metabolic traits (p<0.001). Liver R2* significantly correlated with MHF (AUC=0.77 [0.72-0.82]). MRI-determined pancreatic steatosis (OR=3.15 [1.63-6.09]), and iron overload (OR=2.39 [1.32-4.37]) were independently associated with high-risk CVD. Histologic diagnosis of NASH and advanced fibrosis were also associated with high-risk CVD.

Conclusion

Pancreatic steatosis and iron overload could be of utility in clinical decision-making and prognostication of NAFLD.

Resveratrol protects against deoxynivalenol-induced ferroptosis in HepG2 cells

Deoxynivalenol (DON) is one of the most serious mycotoxins that contaminate food and feed, causing hepatocyte death. However, there is still a lack of understanding regarding the new cell death modalities that explain DON-induced hepatocyte toxicity. Ferroptosis is an iron-dependent type of cell death. The aim of this study was to explore the role of ferroptosis in DON-exposed HepG2 cytotoxicity and the antagonistic effect of resveratrol (Res) on its toxicity, and the underlying molecular mechanisms. HepG2 cells were treated with Res (8μM) or/and DON (0.4μM) for 12hours. We examined cell viability, cell proliferation, expression of ferroptosis-related genes, levels of lipid peroxidation and Fe(II). The results revealed that DON reduced the expression levels of GPX4, SLC7A11, GCLC, NQO1, and Nrf2 while promoting the expression of TFR1, GSH depletion, accumulation of MDA and total ROS. DON enhanced production of 4-HNE, lipid ROS and Fe(II) overload, resulting in ferroptosis. However, pretreatment with Res reversed these changes, attenuating DON-induced ferroptosis, improving cell viability and cell proliferation. Importantly, Res prevented Erastin and RSL3-induced ferroptosis, suggesting that Res exerted an anti-ferroptosis effect by activating SLC7A11-GSH-GPX4 signaling pathways. In summary, Res ameliorated DON-induced ferroptosis in HepG2 cells. This study provides a new perspective on the mechanism of DON-induced hepatotoxicity formation, and Res may be an effective drug to alleviate DON-induced hepatotoxicity.

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.

Analysis of MRI-derived spleen iron in the UK Biobank identifies genetic variation linked to iron homeostasis and hemolysis

The spleen plays a key role in iron homeostasis. It is the largest filter of the blood and performs iron reuptake from old or damaged erythrocytes. Despite this role, spleen iron concentration has not been measured in a large, population-based cohort. In this study, we quantify spleen iron in 41,764 participants of the UK Biobank by using magnetic resonance imaging and provide a reference range for spleen iron in an unselected population. Through genome-wide association study, we identify associations between spleen iron and regulatory variation at two hereditary spherocytosis genes, ANK1 and SPTA1. Spherocytosis-causing coding mutations in these genes are associated with lower reticulocyte volume and increased reticulocyte percentage, while these common alleles are associated with increased expression of ANK1 and SPTA1 in blood and with larger reticulocyte volume and reduced reticulocyte percentage. As genetic modifiers, these common alleles may explain mild spherocytosis phenotypes that have been observed clinically. Our genetic study also identifies a signal that co-localizes with a splicing quantitative trait locus for MS4A7, and we show this gene is abundantly expressed in the spleen and in macrophages. The combination of deep learning and efficient image processing enables non-invasive measurement of spleen iron and, in turn, characterization of genetic factors related to the lytic phase of the erythrocyte life cycle and iron reuptake in the spleen.

Post-mortem liver and bone marrow iron quantification in haemodialysis patients: A prospective cohort study

Background

Magnetic resonance liver scans indicate that iron overload is common in haemodialysis (HD) patients. However, histological evidence is scarce.

Methods

Liver biopsy and bone marrow aspirate were obtained in the first 24h post mortem from 21 adult HD patients. Biochemical liver iron content (LIC) was quantified by electrothermal atomization atomic absorption spectrophotometry. Tissue iron deposition was graded in the liver and bone marrow using Scheuer and Gale's criteria, respectively.

Findings

Median LIC was 42.5 (22.9-69.7) μmol/g and the majority (n=11; 57%) had mild to moderate liver iron overload (LIC >36 μmol/g). Scheuer grade was 2 (1-3) and 13 (62%) of liver biopsies had increased (> 1) iron deposition. In the bone marrow, median Gale's grade was 3 (3-4) and 9 (45%) patients had increased (>3) iron content.

Contrary to old autopsy studies, done in the pre-erythropoiesis-stimulating agents (ESAs) era, both liver and bone marrow were iron replete and showed a positive correlation (r=0.71, p<0.001).

Ferritin proved to have a good diagnostic accuracy for liver iron overload (0.87 95% CI 0.71-1.00) with an optimal cut-off value of 422 ng/ml. Haemoglobin was negatively associated with both LIC (r= -0.46, p=0.04) and iron content in the bone marrow (p=0.04). Patients with increased LIC had higher resistance to ESAs (p=0.02), yet no association with previous IV iron therapy.

Interpretation

In the majority of HD patients there was iron accumulation in both the liver and bone marrow that associated with anaemia severity and resistance to ESAs, suggesting a blocking mechanism of iron's utilization.

Funding

None.

Iron Overload Induces Apoptosis and Cytoprotective Autophagy Regulated by ROS Generation in Mc3t3-E1 Cells

Iron overload has been found very common in diseases such as hereditary hemochromatosis, thalassemia, and sickle cell disease and in healthy postmenopausal women. Recent studies have shown that iron overload is considered an independent risk factor for osteoporosis. Studies have demonstrated that iron overload could induce apoptosis and inhibit viability in osteoblasts. However, the underlying mechanism still remains poorly understood. The purpose of the present study is to investigate possible mechanism of iron overload-induced apoptosis, and the roles autophagy and reactive oxygen species (ROS) played under iron overload conditions. Ferric ammonium citrate (FAC) (100-1600 μM) was utilized as iron donor to induce iron overload conditions. Intracellular iron concentration was measured using Iron Assay Kit. The viability was assessed by CCK-8 assay. Cell apoptosis was examined using Annexin V-FITC/PI staining with a flow cytometry, and levels of Bax, Bcl-2, cleaved caspase-3, and cleaved PARP were evaluated with Western blot. Cell autophagy was detected by evaluating LC3 with immunofluorescence and Western blot. The expressions of Beclin-1 and P62 were also assessed with Western blot. The intracellular ROS level was evaluated using a DCFH-DA probe with a flow cytometry, and NADPH oxidase 4 (Nox4) expressions were assessed with Western blot. Our results showed that FAC increased intracellular iron concentration and significantly inhibited cell viability. Furthermore, iron overload induced apoptosis and autophagy in osteoblast cells. What's more, pretreatment with autophagy inhibitor chloroquine (CQ) enhanced iron overload-induced osteoblast apoptosis via the activation of caspases. Moreover, iron overload increased ROS production and Nox4 expression. Inhibition of autophagy increased ROS production, and scavenging of ROS by antioxidant N-Acetyl-L-cysteine (NAC) inhibited caspases activity and rescued iron overload-induced apoptosis. These results suggested that autophagy exerted cytoprotective effect, and scavenging excessive intracellular ROS could be a novel approach for the treatment of iron overload-induced osteoporosis.

Quantifying Bone Marrow Fat Fraction and Iron by MRI for Distinguishing Aplastic Anemia from Myelodysplastic Syndromes

Background

Bone marrow of patients with aplastic anemia (AA) is different from that of patients with myelodysplastic syndrome (MDS) and is difficult to identify by blood examination. IDEAL‐IQ (iterative decomposition of water and fat with echo asymmetry and least‐squares estimation) imaging might be able to quantify fat fraction (FF) and iron content in bone tissues.

Purpose

To determine if IDEAL‐IQ measurements of bone marrow FF and iron content can distinguish between patients with AA and MDS.

Study Type

Retrospective.

Population

Fifty‐seven patients with AA, 21 patients with MDS, and 24 healthy controls.

Field Strength/Sequence

3.0 T, IDEAL‐IQ sequence.

Assessment

Three independent observers evaluated the IDEAL‐IQ images and measured FF and R2* in the left posterior superior iliac spine.

Statistical Tests

Kruskal–Wallis test, linear correlations, and Bland–Altman analysis were used. A P‐value of <0.05 was considered statistically significant.

Results

The FF in patients with AA (79.46% ± 15.00%) was significantly higher than that in patients with MDS (42.78% ± 30.09%) and control subjects (65.50% ± 14.73%). However, there was no significant difference in FF between control subjects and patients with MDS (P = 0.439). The R2* value of AA, MDS, and controls was 145.38 ± 53.33, (171.13 ± 100.89, and 135.99 ± 32.41/second, respectively, with no significant difference between the three groups (P = 0.553).

Data Conclusion

Quantitative IDEAL‐IQ magnetic resonance imaging may facilitate the diagnosis of AA and distinguish it from MDS.

Level of Evidence

3

Technical Efficacy Stage

2

MRI-based R2* mapping in patients with suspected or known iron overload

PURPOSE

R2* relaxometry is a quantitative method for assessment of iron overload. The purpose is to analyze the cross-sectional relationships between R2* in organs across patients with primary and secondary iron overload. Secondary analyses were conducted to analyze R2* according to treatment regimen.

METHODS

This is a retrospective, cross-sectional, institutional review board-approved study of eighty-one adult patients with known or suspected iron overload. R2* was measured by segmenting the liver, spleen, bone marrow, pancreas, renal cortex, renal medulla, and myocardium using breath-hold multi-echo gradient-recalled echo imaging at 1.5 T. Phlebotomy, transfusion, and chelation therapy were documented. Analyses included correlation, Kruskal-Wallis, and post hoc Dunn tests. p < 0.01 was considered significant.

RESULTS

Correlations between liver R2* and that of the spleen, bone marrow, pancreas, and heart were respectively 0.49, 0.33, 0.27, and 0.34. R2* differed between patients with primary and secondary overload in the liver (p < 0.001), spleen (p < 0.001), bone marrow (p < 0.01), renal cortex (p < 0.001), and renal medulla (p < 0.001). Liver, spleen, and bone marrow R2* were higher in thalassemia than in hereditary hemochromatosis (all p < 0.01). Renal cortex R2* was higher in sickle cell disease than in hereditary hemochromatosis (p < 0.001) and in thalassemia (p < 0.001). Overall, there was a trend toward lower liver R2* in patients assigned to phlebotomy and higher liver R2* in patients assigned to transfusion and chelation therapy.

CONCLUSION

R2* relaxometry revealed differences in degree or distribution of iron overload between organs, underlying etiologies, and treatment.

Adding marrow R2∗ to proton density fat fraction improves the discrimination of osteopenia and osteoporosis in postmenopausal women assessed with 3D FACT sequence

OBJECTIVE

To evaluate the role of three-dimensional Fat Analysis & Calculation Technique sequence in improving the diagnostic accuracy for the detection of osteopenia and osteoporosis by simultaneous quantification of proton density fat fraction (PDFF) and fat-corrected R2∗.

METHODS

Fat Analysis & Calculation Technique imaging of lumbar spine was obtained in 99 postmenopausal women including 52 normal bone mass, 29 osteopenia, and 18 osteoporosis. The diagnostic performance of PDFF and R2∗ in the differentiation of different bone-density groups was evaluated with the receiver operating characteristic curve.

RESULTS

The reproducibility of PDFF and R2∗ measures was satisfactory with the root mean square coefficient of variation, 2.16% and 2.70%, respectively. The intra- and interobserver agreements for the PDFF and R2∗ were excellent with the intraclass correlation coefficient > 0.9 for all. There were significant differences in PDFF and R2∗ among the three groups (P < 0.05). Bone density had a moderate inverse correlation with PDFF (r  = -0.659) but a positive association with R2∗ (r = 0.508, P < 0.001). Adjusted for age, years since menopause and body mass index, odds ratios (95% confidence interval) for osteopenia and osteoporosis per standard deviation higher marrow PDFF and R2∗ were 2.9 (1.4-5.8) and 0.4 (0.2-0.8), respectively. The areas under the curve were 0.821 for PDFF, 0.784 for R2∗, and 0.922 for both combined for the detection of osteoporosis (P < 0.05). Similar results were obtained in distinguishing osteopenia from healthy controls.

CONCLUSIONS

Simultaneous estimation of marrow R2∗ and PDFF improves the discrimination of osteopenia and osteoporosis in comparison with the PDFF or R2∗ alone.

MR imaging assessment and quantification of liver iron

Iron overload is a common clinical problem resulting from hereditary hemochromatosis or secondary hemosiderosis (mainly associated with transfusion therapy), being also associated with chronic liver diseases and metabolic disorders. Excess of iron accumulates in organs like the liver, pancreas and heart. Without treatment, patients with iron overload disorders will develop liver cirrhosis, diabetes and cardiomyopathy. Iron quantification is therefore crucial not only for diagnosis of iron overload but also to monitor iron-reducing therapies. Liver iron concentration is considered the surrogate marker of total body iron stores. Because liver biopsy is invasive and prone to high variability and sampling bias, MR imaging has emerged as a non-invasive method and gained wide acceptance, now being considered the standard of care for assessing iron overload. Nevertheless, there are different MR techniques for iron quantification and there is still no consensus about the best technique or postprocessing tool for hepatic iron quantification, with the choice of imaging technique depending mainly on the local expertise as well on the available equipment and software. Because different methods should not be used interchangeably, it is important to choose one method and use the same one when following up patients over time.

Differences in multi-echo chemical shift encoded MRI proton density fat fraction estimation based on multifrequency fat peaks selection in non-alcoholic fatty liver disease patients

AIM

To compare the performance of multi-echo chemical-shift-encoded (MECSE) magnetic resonance imaging (MRI) proton density fat fraction (PDFF) estimation, considering three different fat frequency peak combinations, for the quantification of steatosis in patients with non-alcoholic fatty liver disease (NAFLD).

MATERIALS AND METHODS

The present study was a prospective cross-sectional research of 121 patients with metabolic syndrome and evidence of hepatic steatosis on ultrasound, who underwent a 3 T MRI examination. All patients were studied with a multifrequency MECSE sequence. The PDFF was calculated using six peaks (MECSE_p123456), three peaks (MECSE_p456), and a single peak (MECSE_p5) model. The two simpler fat peak models were compared to the six peaks model, which was considered the reference standard. Linearity was evaluated using linear regression while agreement was described using Bland-Altman analysis.

RESULTS

The mean age was 47 (±9) years and BMI was 29.9 (±2.9) kg/m². Steatosis distribution was 15%/31%/54% (S1/S2/S3, respectively). Compared to MECSE_p123456, both models provided linear PDFF measurements (R₂= 0.99 and 0.97, MECSE_p456 and MECSE_p5 respectively). Regression slope (0.92; p<0.001) and mean Bland-Altman bias (-1.5%; 95% limits of agreement: -3.19%, 0.22%) indicated minimal underestimation by using PDFF-MECSE_p456. Nonetheless, mean differences in PDFF estimations varied from -1.5% (MECSE_p456,p=0.006) to -2.2% (MECSE_p5,p<0.001) when compared to full six fat frequencies model.

CONCLUSION

Although simpler spectral fat MECSE analysis shows a linear relationship with the standard six peaks model, their variation in estimated PDFF values introduces a low but clinically significant bias in fat quantification and steatosis grading in NAFLD patients.

Practical guide to quantification of hepatic iron with MRI

Abstract

Our intention is to demystify the MR quantification of hepatic iron (i.e., the liver iron concentration) and give you a step-by-step approach by answering the most pertinent questions. The following article should be more of a manual or guide for every radiologist than a classic review article, which just summarizes the literature. Furthermore, we provide important background information for professional communication with clinicians. The information regarding the physical background is reduced to a minimum. After reading this article, you should be able to perform adequate MR measurements of the LIC with 1.5-T or 3.0-T scanners.

Key Points

• MRI is widely accepted as the primary approach to non-invasively determine liver iron concentration (LIC).

• This article is a guide for every radiologist to perform adequate MR measurements of the LIC.

• When using R2* relaxometry, some points have to be considered to obtain correct measurements—all explained in this article.