Iron status determination in individuals with Helicobacter pylori infection: conventional vs. new laboratory biomarkers

Association of soluble transferrin receptor/log ferritin index with all-cause and cause-specific mortality: National Health and Nutrition Examination Survey

Background

Soluble transferrin receptor (sTfR)/log ferritin index (sTfR Index) can be used to assess the entire spectrum of iron status, and is valuable in evaluating iron status in population studies. There is still a lack of evidence on the association between sTfR index and all-cause mortality.

Object

To explore the association between sTfR index and all-cause mortality, as well as mortality due to cardiovascular disease (CVD) and cancer.

Method

Data were from the National Health and Nutrition Examination Survey (NHANES) between 2003 to 2020. Participants aged 16 years and older who had complete data of serum ferritin and sTfR were included. Pregnant individuals or those with ineligible data on death or follow-up were excluded from the analysis. Baseline sTfR index was calculated by baseline sTfR/log (ferritin) and classified as three tertile. We performed the Cox proportional hazard regression to assess the association of sTfR index (both continuous and categorical scale) with all-cause and cause-specific mortality and further assess the non-linear relationship between sTfR index and the outcomes with restricted cubic spline.

Result

In this study, 11,525 participants, a total of 231 (2.0%) all-cause deaths occurred during a median follow-up of 51 months. The risk of all-cause mortality, CVD-related mortality, and cancer-related mortality was higher in participants with highest tertile of sTfR index. After confounding factors adjustment, participants with highest tertile of sTfR index were associated with an increased risk of all-cause mortality (HR: 1.71, 95% CI: 1.14-2.57) as compared with lowest tertile. Additionally, sTfR index per SD increment was associated with a 25% increasing risk of all-cause mortality (HR: 1.25, 95% CI: 1.08-1.45, p = 0.003) and a 38% cancer-related mortality (HR: 1.38, 95% CI: 1.07-1.77, p = 0.018). These associations remained robust after adjusting for the serum ferritin as well as in various subgroups stratified by age, sex, smoking statue, hypertension, diabetes, and CVD. Spline analysis showed that there is approximately linear relationship between sTfR index with all-cause mortality (p for non-linear = 0.481). Moreover, ferritin was not a predictor of all-cause death after adjustment for confounding factors.

Significance

This cohort study demonstrated a significant association between sTfR index increment and an increased risk of all-cause and cancer-related mortality, independent of ferritin levels.

The putative role of ferroptosis in gastric cancer: a review

Ferroptosis is a unique cell death modality triggered by iron-dependent lipid peroxidation, with cysteine metabolism and glutathione-dependent antioxidant defence responses as the primary triggering mechanisms. Ferroptosis is an independent tumour suppression mechanism and has been implicated in various disorders. In tumourigenesis, ferroptosis plays a dual role in promoting and inhibiting tumours. P53, NFE2L2, BAP1, HIF, and other tumour suppressor genes regulate ferroptosis, releasing damage-associated molecular patterns or lipid metabolites to influence cellular immune responses. Ferroptosis is also involved in tumour suppression and metabolism. The combination of amino acid, lipid, and iron metabolism is involved in the initiation and execution of ferroptosis, and metabolic regulatory mechanisms also play roles in malignancies. Most investigations into ferroptosis in gastric cancer are concentrated on predictive models, not the underlying processes. This review investigates the underlying mechanisms of ferroptosis, tumour suppressor genes, and the tumour microenvironment.

The alternative Thomas-plot: A new tool for effective anemia diagnostics

INTRODUCTION

The Thomas-plot has proven to be a helpful tool to discriminate between different types of anemia. This plot combines the reticulocyte hemoglobin content (Ret-He) with the soluble transferrin receptor (sTfR)/log ferritin (fer) ratio. In this study, we designed an alternative Thomas-plot in which Ret-He is combined with the transferrin (Tf)/log ferritin ratio. We validated both Thomas-plots in a population of anemic patients and compared the performance to the current laboratory diagnostics of anemia.

METHODS

A total of 536 anemic patients were included. The first 188 patients were used to generate ROC curves to define the optimal cut-off values for both Thomas-plots. With the following 348 patients included we studied the performance of the alternative and classical Thomas-plots compared to current anemia diagnostics.

RESULTS

Cut-off values were defined (Ret-He: 31.2 pg, sTfR/log(fer): 0.91, and Tf/log(fer): 1.71). With both Thomas-plots the amount of e causa ignota (ECI) cases dropped from 39% to 27%. A more in depth analysis on the iron status of anemia of chronic disease (ACD) patients and a subdivision between latent and classical iron deficiencies could be made with the help of both plots. A shift from classical iron deficiency anemia (IDA) cases according to the classical Thomas-plot toward functional IDA according to the alternative Thomas-plot was observed.

CONCLUSION

The alternative Thomas-plot is an effective tool that gives a more in depth view on the iron status of anemic patients. In addition, it is easier to implement due to the use of transferrin rather than the soluble transferrin receptor.

Epstein-Barr Virus Infection Is Associated with Elevated Hepcidin Levels

EBV and Helicobacter pylori (H. pylori) cause highly prevalent persistent infections as early as in childhood. Both pathogens are associated with gastric carcinogenesis. H. pylori interferes with iron metabolism, enhancing the synthesis of acute-phase proteins hepcidin, C-reactive protein (CRP), and α-1 glycoprotein (AGP), but we do not know whether EBV does the same. In this study, we correlated the EBV antibody levels and the serum levels of hepcidin, CRP, and AGP in 145 children from boarding schools in Mexico City. We found that children IgG positive to EBV antigens (VCA, EBNA1, and EA) presented hepcidin, AGP, and CRP levels higher than uninfected children. Hepcidin and AGP remained high in children solely infected with EBV, while CRP was only significantly high in coinfected children. We observed positive correlations between hepcidin and EBV IgG antibodies (p < 0.5). Using the TCGA gastric cancer database, we also observed an association between EBV and hepcidin upregulation. The TCGA database also allowed us to analyze the two important pathways controlling hepcidin expression, BMP−SMAD and IL-1β/IL-6. We observed only the IL-1β/IL-6-dependent inflammatory pathway being significantly associated with EBV infection. We showed here for the first time an association between EBV and enhanced levels of hepcidin. Further studies should consider EBV when evaluating iron metabolism and anemia, and whether in the long run this is an important mechanism of undernourishment and EBV gastric carcinogenesis.

Comparison of two LC-MS/MS methods for the quantification of 24,25-dihydroxyvitamin D3 in patients and external quality assurance samples

OBJECTIVES

In-house developed liquid-chromatography mass spectrometry (LC-MS/MS) methods are used more and more frequently for the simultaneous quantification of vitamin D metabolites. Among these, 24,25-dihydroxyvitamin D3 (24,25(OH)₂D₃) is of clinical interest. This study assessed the agreement of this metabolite in two validated in-house LC-MS/MS methods.

METHODS

24,25(OH)₂D₃ was measured in 20 samples from the vitamin D external quality assurance (DEQAS) program and in a mixed cohort of hospital patients samples (n=195) with the LC-MS/MS method at the Medical University of Graz (LC-MS/MS 1) and at the University of Liège (LC-MS/MS 2).

RESULTS

In DEQAS samples, 24,25(OH)₂D₃ results with LC-MS/MS 1 had a proportional bias of 1.0% and a negative systemic difference of -0.05%. LC-MS/MS 2 also showed a proportional bias of 1.0% and the negative systemic bias was -0.22%. Comparing the EQA samples with both methods, no systemic bias was found (0.0%) and the slope was 1%. The mean difference of 195 serum sample measurements between the two LC-MS/MS methods was minimal (-0.2%). Both LC-MS/MS methods showed a constant bias of 0.31 nmol/L and a positive proportional bias of 0.90%, respectively.

CONCLUSIONS

This study is the first to assess the comparability of 24,25(OH)₂D₃ concentrations in a mixed cohort of hospitalized patients with two fully validated in-house LC-MS/MS methods. Despite different sample preparation, chromatographic separation and ionization, both methods showed high precision measurements of 24,25(OH)₂D₃. Furthermore, we demonstrate the improvement of accuracy and precision measurements of 24,25(OH)₂D₃ in serum samples and in the DEQAS program.

Branched-chain amino acids are linked with iron metabolism

Background

The branched-chain amino acids (BCAAs) valine, leucine and isoleucine are reported to influence erythropoiesis and the human iron status. Large study cohorts encompassing biomarkers of iron metabolism and BCAAs are still lacking.

Methods

We investigated potential interactions between blood concentrations of all three BCAAs valine, leucine and isoleucine and biomarkers of iron metabolism [i.e., hemoglobin (Hb), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), iron, transferrin, ferritin, transferrin saturation, soluble transferrin receptor (sTfR)] in 430 outpatients referred for a medical health check-up. Linear regression models were performed to assess possible associations between variables.

Results

All three BCAAs were positively correlated with Hb, ferritin and the sTfR (r-values: 0.145–0.382; P values: <0.001–0.003). The strongest correlation was observed between valine and Hb (r=0.382; P value <0.001). Linear regression models showed a statistically significant influence of all three BCAAs on Hb and ferritin (β-coefficients: 0.173–0.351; all P values: <0.001). Seventeen patients with anemia (4%) were found with significantly lower serum BCAA concentrations compared to 413 non-anemic individuals (P<0.05).

Conclusions

These data indicate a pathophysiological link between the three BCAAs valine, leucine and isoleucine and the human iron indicators Hb and ferritin. Further studies are needed to clarify the exact causal mechanisms of these findings.