Association between iron status markers and kidney outcome in patients with chronic kidney disease

The Interplay Between Carotid Intima-Media Thickness and Selected Serum Biomarkers in Various Stages of Chronic Kidney Disease

Background/Objectives: Chronic kidney disease (CKD), the most common cause of which is hypertension and diabetes, is a recognized risk factor for cardiovascular disease (CVD). This study investigated the association between selected serum biomarkers in the context of intima-media thickness (IMT) changes, a common predictor of subsequent cardiovascular (CV) events. Methods: A total of 251 individuals were enrolled in the study, divided into groups based on the severity of CKD, the presence of CVD, and healthy controls. For this purpose, the data from the following groups of participants were analyzed: (1) end-stage renal disease (ESRD) (n = 106), (2) pre-dialyzed (PRE) (n = 48), (3) patients at stages 1 and 2 of CKD (CKD1-2) (n = 37), (4) patients with CVD and no kidney disease (CARD) (n = 28), and (5) healthy controls (HV) (n = 31). To find markers associated with elevated IMT, the each group with CVD (ESRD, PRE and CARD) was separated into two subgroups with normal and elevated IMT and compared in the relation of the studied serum biomarkers. Results: The findings identified glucose as the only marker exclusively associated with CVD. Markers uniquely linked to CKD included urea, creatinine, eGFR, total protein, CEL, neopterin, total calcium, phosphates, iPTH, sodium, iron, ferritin, and AST. All other markers reflected a combined influence of both CKD and CVD. By comparing patients with normal and elevated IMT, distinct types of CKD-CVD interactions were observed, i.e., independent (additive effects of CKD and CVD) for MPO, ALP, MMP-9, and MMP-9/TIMP-1; combined (enhanced effect due to interactions) for AOPPs and TIMP-1; and conditional (CVD impact specific to CKD patients) for AGEs, 3-NT, magnesium, UIBC, TIBC, ALT, and TIMP-1/MMP-9. However, certain markers, i.e., CML, sRAGEs, carbamylated protein groups, protein carbamylation, hsCRP, TC, HDL-C, LDL-C, TG, IL-18, klotho, FGF-23, klotho/FGF-23 ratio, potassium, NT-proBNP, and AIP were associated with both CKD and CVD, though the exact nature of their interaction could not be determined using IMT as a distinguishing factor. Conclusions: The results showed that relations between IMT and the remaining studied factors were not trivial, and most of the analyzed parameters were altered in CKD patients, especially if compared to patients with CVD but without CKD. IMT cannot be used as a universal CVD marker.

Mapping a Decade of Research: Bibliometric Analysis of Iron Overload in Chronic Kidney Disease

This study conducts a bibliometric analysis (BA) to map the research landscape surrounding chronic kidney disease (CKD) and iron overload over the past decade. Utilizing PubMed as the primary database, a systematic search strategy was developed using BA guidelines, incorporating keyword and MeSH term refinements for comprehensive data retrieval. A Boolean operator-based search strategy was applied, capturing literature from 2014 to the first quarter of 2024, with inclusion criteria focusing on articles and review articles published in English. An initial pool of 408 records was narrowed to 52 articles after applying filters and exclusions based on relevance and document type. Data analysis employed the Java-based bibliometric tool VOSviewer, facilitating citation analysis, keyword co-occurrence mapping, and network visualization of author and institutional contributions. MeSH terms and keywords were analyzed for frequency and signal strength, with "Humans," "Iron," and "Iron Overload" emerging as dominant terms. Trends in publication activity from 2014 to 2024 revealed cyclic patterns influenced by external factors. The institutional analysis highlighted contributions from key healthcare and research institutions globally. The findings underline significant themes, contributors, and research gaps within the field, providing valuable insights for future CKD and iron management studies. This study not only identifies major trends and collaborative networks but also highlights potential areas for advancing patient care and treatment strategies for CKD patients with iron-related conditions.

Associations between serum mineral concentrations and mortality by renal function in the Ludwigshafen Risk and Cardiovascular Health Study

The association of serum concentrations of minerals and phosphate with overall and cardiovascular mortality based on renal function is poorly understood. 3307 patients (average age 62.7 ± 10.6 years) in the Ludwigshafen Risk and Cardiovascular Health (LURIC) study were grouped by estimated glomerular filtration rate (eGFR) into three categories: < 60, 60-89, and ≥ 90 mL/min per 1.73 m2, per KDIGO 2022 guidelines and were analysed using Cox regression. Low serum sodium and iron concentrations were associated with poor renal function and increased overall mortality risk, whereas higher serum zinc concentrations were associated with reduced overall and cardiovascular mortality risk. Elevated serum copper concentrations were associated with increased mortality risk across all eGFR categories. Comparing low and normal eGFR, we observed a fourfold increase in all-cause mortality risk for eGFR < 60 mL/min per 1.73 m2 and a twofold increase for eGFR 60-89 mL/min per 1.73 m2, accompanied by changes in serum mineral concentrations. The optimal range of mineral and phosphate concentrations in serum was strongly related to renal function. To reduce mortality risk, it's important to regularly monitor serum mineral and phosphate concentrations as well as renal function, especially in cardiovascular patients with compromised renal function.

PBMC therapy reduces cell death and tissue fibrosis after acute kidney injury by modulating the pattern of monocyte/macrophage survival in tissue

In this study, we investigated if the therapeutic potential of peripheral blood mononuclear cell (PBMC) therapy in a murine model of ischemic AKI is related with the survival pattern of monocyte/macrophages in tissue. CD-1 mice were subjected to bilateral renal ischemia followed by reperfusion to induce AKI. M2-polarized PBMCs isolated from CD-1 mice were administered intravenously at different time points post-injury. Our results demonstrate that early administration of PBMC therapy attenuates renal tissue damage, reduces tissue cell death and prevents fibrosis development. Reduction of tissue pyroptosis was observed by reduction on NLRP3 inflammasome activation and decreasing IL-1beta and Caspase-1 expression in the kidney. Furthermore, the therapy was shown to mitigate ferroptosis by inducing GPX4 overexpression. Early administration of PBMCs increased the survival pattern of renal tissue-macrophages, promoting a "pro-survival phenotype" resulting in decreased pyroptotic marker NLRP3, IL-1beta and Caspase 1 and increased anti-ferroptotic gene GPX4. Conversely, delayed administration of PBMC therapy exhibits diminished efficacy in preventing cell death and fibrosis in tissue and provoked a decrease in the pro-survival phenotype of both monocyte /macrophages in tissue. Our findings highlight the therapeutic potential of PBMC therapy in mitigating AKI and preventing CKD progression by modulating tissue-resident macrophage survival and reducing their cell death pathways. The fact that the effectiveness of the therapy depends on the time of administration after the injury underscores the importance of early intervention in AKI management.

Iron-induced kidney cell damage: insights into molecular mechanisms and potential diagnostic significance of urinary FTL

Background: Iron overload can lead to organ and cell injuries. Although the mechanisms of iron-induced cell damage have been extensively studied using various cells, little is known about these processes in kidney cells. Methods: In this study, we first examined the correlation between serum iron levels and kidney function. Subsequently, we investigated the molecular impact of excess iron on kidney cell lines, HEK293T and HK-2. The presence of the upregulated protein was further validated in urine. Results: The results revealed that excess iron caused significant cell death accompanied by morphological changes. Transcriptomic analysis revealed an up-regulation of the ferroptosis pathway during iron treatment. This was confirmed by up-regulation of ferroptosis markers, ferritin light chain (FTL), and prostaglandin-endoperoxide synthase 2 (PTGS2), and down-regulation of acyl-CoA synthetase long-chain family member 4 (ACSL4) and glutathione peroxidase 4 (GPX4) using real-time PCR and Western blotting. In addition, excess iron treatment enhanced protein and lipid oxidation. Supportively, an inverse correlation between urinary FTL protein level and kidney function was observed. Conclusion: These findings suggest that excess iron disrupts cellular homeostasis and affects key proteins involved in kidney cell death. Our study demonstrated that high iron levels caused kidney cell damage. Additionally, urinary FTL might be a useful biomarker to detect kidney damage caused by iron toxicity. Our study also provided insights into the molecular mechanisms of iron-induced kidney injury, discussing several potential targets for future interventions.