Transferrin (TF) is a key iron carrier protein. Studies in human cohorts and in cultured adipocytes suggested that decreased transferrin expression and intracellular iron in adipocytes leads to impaired insulin responsiveness and causes differential expression of genes involved in metabolism, insulin action, and obesity. While suggestive, these studies did not definitively prove in an intact organism that altering TF expression in adipocytes is sufficient to affect glucose homeostasis and insulin resistance. In this study we created a mouse model of decreased transferrin expression only in adipocytes (Trf+/-Cre+/-) to test the hypothesis that iron trafficking in adipose tissue is sufficient to affect insulin sensitivity. Area under the glucose curve (AUCg) after intraperitoneal glucose administration was increased in the Trf+/-Cre+/- mice compared to wild type (WT) mice on a normal chow diet, and the mice were slightly heavier (p=0.02 for both). Homeostasis Model of Insulin Resistance (HOMA-IR) values were also significantly higher in the Trf+/- Cre+/- mice (p<0.05). Thus, supporting our hypothesis, analysis of mice with decreased expression of TF restricted to adipocytes showed that a decrease in adipocyte TF is sufficient to affect insulin resistance, weight, and glucose homeostasis.

The blood-brain barrier (BBB), built by brain endothelial cells (BECs), is impermeable to biologics. Liposomes and other nanoparticles are good candidates for delivery of biologics across the BECs, as they can encapsulate numerous molecules of interest in an omnipotent manner. The liposomes need attachment of a targeting molecule, as BECs unfortunately are virtually incapable of uptake of non-targeted liposomes from the circulation. Experiments of independent research groups have qualified antibodies targeting the transferrin receptor as superior for targeted delivery of nanoparticles to BECs. Functionalization of nanoparticles via conjugation with anti-transferrin receptor antibodies leads to nanoparticle uptake by endothelial cells of both brain capillaries and post-capillary venules. Reducing the density of transferrin receptor-targeted antibodies conjugated to liposomes limits uptake in BECs. Opposing the transport of nanoparticles conjugated to high-affine anti-transferrin receptor antibodies, lowering the affinity of the targeting antibodies or implementing monovalent antibodies increase uptake by BECs and allows for further transport across the BBB. The novel demonstration of transport of targeted liposomes in post-capillary venules from blood to the brain is interesting and clearly warrants further mechanistic pursuit. The recent evidence for passing targeted nanoparticles through the BBB shows great promise for future drug delivery of biologics to the brain.

Ferritin is an indirect marker for total body iron stores. Comparison of the ferritin concentrations in the meconium with the concentrations of proteins regulating iron metabolism could aid better understanding of principles behind the adjustment between the fetal iron pool and newborn body size. Ferritin, transferrin, haptoglobin, ceruloplasmin, lactoferrin, myeloperoxidase, neutrophil gelatinase-associated lipocalin (NGAL) and calprotectin concentrations were measured by ELISA in meconium samples from 122 neonates. The neonates were classified according to the meconium ferritin tertiles and the values were collated with the meconium concentrations of other proteins and newborn body weight and length measurements. Increasing ferritin concentrations in meconium in consecutive tertiles (p < 0.05) were parallel to increased NGAL concentrations (p < 0.05). The interrelationships between the meconium concentrations of transferrin, haptoglobin and NGAL as well as between myeloperoxidase, calprotectin and lactoferrin are maintained in all subsequent tertiles of ferritin concentrations, (p < 0.05). In contrast to ferritin, increasing meconium NGAL concentrations in consecutive tertiles were linked to increased concentrations of transferrin, haptoglobin, lactoferrin and myeloperoxidase (p < 0.05) and of calprotectin, ferritin and ceruloplasmin (p < 0.1). Meconium ceruloplasmin concentrations correlate exclusively with neutrophil granule proteins, i.e. myeloperoxidase, NGAL, lactoferrin and calprotectin (p < 0.05). Meconium ferritin concentrations negatively correlates with birth weight (r= -0.20) and length (r= -0.31) of neonates, whereas NGAL concentrations just with birth length (r= -0.26). The remaining proteins did not show such relationships with the size of the newborn. High meconium concentrations of both ferritin and NGAL may specifically characterize neonates of smaller size. High meconium concentrations of both ferritin and NGAL may specifically characterize neonates with lower body measurements. Correlations between meconium transferrin, haptoglobin and NGAL may confirm the interrelationships of these proteins for proper iron control and transport in the intrauterine environment. Meconium ceruloplasmin concentrations may reflect the control of neutrophil activity in utero.

Glycosylation, the most significant modification of proteins, plays an essential role in cellular processes. Congenital disorders of glycosylation (CDG) are multisystemic diseases resulting from mutations affecting glycosylation steps. Diagnosis of CDG relies on biochemical assays, such as isoelectric focusing. Despite its significance, CDG cases remain unreported in Cuba due to the lack of implemented diagnostic methods. This study aimed to evaluate transferrin glycoforms for diagnosing congenital N-glycosylation defects. We conducted a cross-sectional descriptive study using serum samples from 17 patients stored at the National Center for Medical Genetics of Cuba for suspected CDG. Results revealed abnormal glycosylation patterns in 7 patients, suggesting congenital N-glycosylation defects. We conclude that the implementation of transferrin glycoform analysis could pioneer a preliminary diagnosis of CDG in Cuba.

(1) Background: The aim of this study was to analyze the relationship between the serum levels of soluble transferrin receptor (sTfR) and interleukin 4 (IL-4), and disease activity and organ mani-festations in SLE patients. (2) Methods: We studied 200 SLE patients and 50 controls. We analyzed disease activity, organ involvement, serum sTfR, IL-4, and interleukin-6 (IL-6) levels, and antinu-clear and antiphospholipid antibody profiles. (3) Results: The median serum levels of sTfR (p>0.000001) and IL-4 (p<0.00001) were higher in the study group than in the controls. SLE patients, compared to the controls, had significantly lower HGB levels (p<0.0001), a lower iron concentration (p=0.008), a lower value of total iron-binding capacity (TIBC) (p=0.03), and lower counts of RBC (p=0.004), HCT (p=0.0004), PLT (p=0.04), neutrophil (p=0.04), and lymphocyte (p<0.0001). Serum sTfR levels were negatively correlated with lymphocyte (p=0.0005), HGB (p=0.0001) and HCT (p=0.008), and positively correlated with IL-4 (p=0.01). Elevated serum sTfR >2.14 mg/dL was associated with an increased risk of myocardial infarction (OR: 10.6 95 CI 2.71–464.78; p=0.001), ischemic heart disease (OR: 3.25 95 CI 1.02–10.40; p=0.04), lung manifestations (OR: 4.48 95 CI 1.44–13.94; p=0.01), and hematological manifestations (OR: 2.07 95 CI 1.13–3.79; p=0.01), and with a reduced risk of neuropsychiatric manifestations (OR: 0.42 95 CI 0.22–0.80; p=0.008). Serum IL-4 was negatively correlated with CRP (p=0.003), and elevated serum IL-4 levels > 0.17 mg/l were associated with a reduced risk of mucocutaneous manifestations (OR: 0.48 95 CI 0.26–0.90; p=0.02). (4) Conclusions: In SLE patients, elevated serum levels of sTfR were associated with an increased risk of cardiovascular, pulmonary, and hematological manifestations, and with a decreased risk of neuropsychiatric manifestations. In contrast, elevated serum IL-4 levels were associated with a decreased risk of mucocutaneous manifestations.

Iron metabolism plays a crucial role in the management of hemoglobinopathies, particularly in conditions such as β-thalassemia and sickle cell anemia (SCA). This paper describes the mechanisms of iron overload in patients with transfusion-dependent thalassemia (TDT), non-transfusion-dependent thalassemia (NTDT), and SCA, highlighting the distinct paths leading to iron accumulation in each condition. The primary focus of this review article is on the role of genetic modifiers influencing iron metabolism and the variability in iron overload presentation among patients. Genetic mutations in genes such as HFE, HAMP, TFR2, SLC40A1, and others significantly impact iron regulation. These modifiers can exacerbate or ameliorate iron overload, and understanding these genetic factors is important for explaining the diverse disease severity and differences in the mechanism and clinical presentation of iron overload in these patients. The ongoing INHERENT study aims to further elucidate the influence of these genetic modifiers through a comprehensive genome-wide association study, potentially leading to novel therapeutic interventions for managing iron homeostasis in hemoglobinopathy patients.

Serum transferrin (sTf) plays a pivotal role in regulating iron biodistribution and homeostasis within the body. The molecular details of sTf Fe(III) binding, blood transport, and cellular delivery through transferrin receptor-mediated endocytosis are generally well-understood. Emerging interest exists in exploring sTf complexation of nonferric metals as it facilitates the therapeutic potential and toxicity of several of them. This review explores recent X-ray structural and physiologically relevant metal speciation studies to understand how sTf partakes in the bioactivity of key non-redox active hard Lewis acidic metals. It challenges preconceived notions of sTf structure function correlations that were based exclusively on the Fe(III) model by revealing distinct coordination modalities that nonferric metal ions can adopt and different modes of binding to metal-free and Fe(III)-bound sTf that can directly influence how they enter into cells and, ultimately, how they may impact human health. This knowledge informs on biomedical strategies to engineer sTf as a delivery vehicle for metal-based diagnostic and therapeutic agents in the cancer field. It is the intention of this work to open new avenues for characterizing the functionality and medical utility of nonferric-bound sTf and to expand the significance of this protein in the context of bioinorganic chemistry.

The aim of this study was to analyze other possible new markers of severity that can be assessed in patients with type 2 diabetes and SARS-CoV-2 (Severe acute respiratory syndrome coronavirus 2) infection. Our study included 90 subjects: 45 patients with type 2 diabetes mellitus and infected with the SARS-CoV-2 virus, and 45 healthy persons as control. The serum level of ceruloplasmin at hospital admission was statistically significant directly correlated with the severity of COVID-19 (Coronavirus disease) (p=0.037) and with the serum level of IL-6 (Interleukine 6) (p=0.000). Ceruloplasmin was statistically significant inversely correlated with serum iron level (p=0.000). However, we observed that ACE (Angiotensin converting enzyme) decreased in severe forms of the infection with SARS-CoV-2 virus in patients with type 2 diabetes (p=0.001). Moreover, the decrease in ACE level was correlated with an increase in IL-6 level in these patients (p=0.001). IL-6 increase was statistically significant inversely correlated with serum iron, transferrin and ACE levels. There was a noticed a decreasing tendency of the transferrin depending on the severity of the COVID-19 infection (p=0.000). In addition to the known severity factors in the context of infection with the new coronavirus, decreased concentrations of ceruloplasmin, ACE and transferrin may represent new markers of COVID-19 severity in patients with type 2 diabetes. These parameters analyzed at the hospital admission could show the evolution towards the severe forms of infection with the SARS-CoV-2 virus.

Background. Transferrin receptor 1 (TfR1), glucose transporter 1 (GLUT1), and CD98hc are candidates for targeted therapy at the blood-brain barrier (BBB). Our objective was to challenge the expression of TfR1, GLUT1, and CD98hc in brain capillaries by the histone deacetylase inhibitor (HDACi) valproic acid (VPA). Methods. Primary mouse brain capillary endothelial cells (BCECs) and brain capillaries isolated from mice injected intraperitoneally with VPA were examined using RT-qPCR and ELISA. Targeting to the BBB was performed by injecting monoclonal anti-TfR1 (Ri7217)-conjugated gold nanoparticles measured using ICP-MS. Results. In BCECs co-cultured with glial cells, Tfrc mRNA expression was significantly higher after 6 h VPA returning to baseline after 24 h. In vivo Glut1 mRNA expression was significantly higher in males, but not females', receiving VPA, whereas Cd98hc mRNA expression was unaffected by VPA. TfR1 increased significantly in vivo after VPA, whereas GLUT1 and CD98hc were unchanged. Uptake of anti-TfR1-conjugated nanoparticles was unaltered by VPA in spite upregulated TfR expression. Conclusions. VPA upregulates TfR1 in brain endothelium in vivo and in vitro. VPA does not increase GLUT1 and CD98hc proteins. The increase in TfR1 does not result in higher anti-TfR1 antibody targetability, suggesting targeting sufficiently occurs with available transferrin receptors without further contribution from accessory VPA-induced TfR1.

The streptavidin and biotin interaction is one of the strongest non-covalent interactions in nature. As a result, this non-covalent interaction has been of great interest when it comes to biochemical assays, diagnosis of diseases, and cell-targeted drug delivery. Past research has proven that biotin-streptavidin is useful in biosensor development to improve the detection of a system when conjugated to nanoparticles. This study aims to prove that streptavidin-coated nanoparticles can be conjugated with biotinylated antibodies using the primary-secondary method to non-invasively detect adenocarcinoma in-vitro. While the use of nanoparticles is not uncommon to the diagnostics area of scientific research, the technique this research aims to investigate is a non-invasive one, utilizing the primary-secondary method. Specifically, the increased stability of fluorophores when bound to antibodies as opposed to nanoparticles directly can be indicative of the particles conjugated through the primary-secondary method’s ability to specifically bind to overexpressed transferrin receptors in the A549 cell line. In this paper, streptavidin-coated nanoparticles were conjugated with biotinylated anti-transferrin receptor antibodies and AlexaFluor-488 secondary antibodies were used to enable fluorescence-based detection. The efficiency of these particles were observed quantitatively through a plate reader and qualitatively through a fluorescence microscope. I demonstrated that these nanoparticles are able to specifically bind to the target proteins in this study. These findings contribute to the field of nanoparticle diagnostics and can be extended to different diseases caused by overexpression of proteins in the future. While this was conducted in-vitro, conjugates can be prepared to detect cancer in-vivo and can be tested with magnetic relaxometry in the future.