Lung surfactant is a complex mixture of phospholipids and surfactant proteins that is produced in alveolar type 2 cells. It prevents lung collapse by reducing surface tension and is involved in ...innate immunity. Exogenous animal-derived and, more recently, synthetic lung surfactant has shown clinical efficacy in surfactant-deficient premature infants and in critically ill patients with acute respiratory distress syndrome (ARDS), such as those with severe COVID-19 disease. COVID-19 pneumonia is initiated by the binding of the viral receptor-binding domain (RBD) of SARS-CoV-2 to the cellular receptor angiotensin-converting enzyme 2 (ACE2). Inflammation and tissue damage then lead to loss and dysfunction of surface activity that can be relieved by treatment with an exogenous lung surfactant. Surfactant protein B (SP-B) is pivotal for surfactant activity and has anti-inflammatory effects. Here, we study the binding of two synthetic SP-B peptide mimics, Super Mini-B (SMB) and B-YL, to a recombinant human ACE2 receptor protein construct using molecular docking and surface plasmon resonance (SPR) to evaluate their potential as antiviral drugs. The SPR measurements confirmed that both the SMB and B-YL peptides bind to the rhACE2 receptor with affinities like that of the viral RBD-ACE2 complex. These findings suggest that synthetic lung surfactant peptide mimics can act as competitive inhibitors of the binding of viral RBD to the ACE2 receptor.
Recovery from blood loss requires a greatly enhanced supply of iron to support expanded erythropoiesis. After hemorrhage, suppression of the iron-regulatory hormone hepcidin allows increased iron ...absorption and mobilization from stores. We identified a new hormone, erythroferrone (ERFE), that mediates hepcidin suppression during stress erythropoiesis. ERFE is produced by erythroblasts in response to erythropoietin. ERFE-deficient mice fail to suppress hepcidin rapidly after hemorrhage and exhibit a delay in recovery from blood loss. ERFE expression is greatly increased in Hbb(th3/+) mice with thalassemia intermedia, where it contributes to the suppression of hepcidin and the systemic iron overload characteristic of this disease.
Erythroferrone (ERFE) is an erythropoiesis-driven regulator of iron homeostasis. ERFE mediates the suppression of the iron-regulatory hormone hepcidin to increase iron absorption and mobilization of ...iron from stores. We examined the role of ERFE in the recovery from anemia of inflammation (AI) induced by injection of heat-killed Brucella abortus. B abortus–treated wild-type mice developed a moderate anemia and reached nadir hemoglobin 14 days after injection and partially recovered by 28 days. We observed that Erfe expression in the bone marrow and the spleen was greatly increased during anemia and peaked at 14 days after injection, a time course similar to serum erythropoietin. To determine whether ERFE facilitates the recovery from anemia, we analyzed Erfe-deficient mice injected with B abortus. Compared with wild-type mice, Erfe-deficient mice exhibited a more severe anemia, had higher hepcidin levels and consequently lower serum iron concentration on days 14 and 21, and manifested impaired mobilization of iron from stores (liver and spleen). Erfe−/− mice eventually compensated by further stimulating erythropoiesis and reticulocyte production. Thus, ERFE contributes to the recovery from AI by suppressing hepcidin and increasing iron availability.
•Mice lacking ERFE have more severe and prolonged AI.•ERFE suppresses hepcidin and mobilizes iron to accelerate recovery from AI.
Nonclassical ferroportin disease (FD) is a form of hereditary hemochromatosis caused by mutations in the iron transporter ferroportin (Fpn), resulting in parenchymal iron overload. Fpn is regulated ...by the hormone hepcidin, which induces Fpn endocytosis and cellular iron retention. We characterized 11 clinically relevant and 5 nonclinical Fpn mutations using stably transfected, inducible isogenic cell lines. All clinical mutants were functionally resistant to hepcidin as a consequence of either impaired hepcidin binding or impaired hepcidin-dependent ubiquitination despite intact hepcidin binding. Mapping the residues onto 2 computational models of the human Fpn structure indicated that (1) mutations that caused ubiquitination-resistance were positioned at helix-helix interfaces, likely preventing the hepcidin-induced conformational change, (2) hepcidin binding occurred within the central cavity of Fpn, (3) hepcidin interacted with up to 4 helices, and (4) hepcidin binding should occlude Fpn and interfere with iron export independently of endocytosis. We experimentally confirmed hepcidin-mediated occlusion of Fpn in the absence of endocytosis in multiple cellular systems: HEK293 cells expressing an endocytosis-defective Fpn mutant (K8R), Xenopus oocytes expressing wild-type or K8R Fpn, and mature human red blood cells. We conclude that nonclassical FD is caused by Fpn mutations that decrease hepcidin binding or hinder conformational changes required for ubiquitination and endocytosis of Fpn. The newly documented ability of hepcidin and its agonists to occlude iron transport may facilitate the development of broadly effective treatments for hereditary iron overload disorders.
•Analysis of mutations causing nonclassical FD defined the hepcidin-binding site in the central cavity of Fpn.•Hepcidin inhibits iron export through Fpn not only by causing Fpn endocytosis, but also by occluding the transporter.
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Erythroferrone (ERFE) is a glycoprotein hormone secreted by erythroblasts in response to stimulation by erythropoietin (EPO). We previously demonstrated that ERFE messenger RNA expression and serum ...protein concentration increase in mice subjected to hemorrhage or EPO therapy, that ERFE acts on hepatocytes to suppress hepcidin, and that the resulting decrease in hepcidin augments iron delivery for intensified erythropoiesis. We also showed that ERFE contributes to pathological hepcidin suppression and iron overload in mice with nontransfused β-thalassemia. We now report the development and technical validation of a rabbit monoclonal antibody–based sandwich immunoassay for human ERFE. We use this assay to show that blood loss or EPO administration increases serum ERFE concentrations in humans, and that patients with both nontransfused and transfused β-thalassemia have very high serum ERFE levels, which decrease after blood transfusion. The assay should be useful for human studies of normal and disordered erythropoiesis and its effect on iron homeostasis.
•Human serum ERFE shows similar pathophysiological responses to mouse models.
Hereditary hemochromatosis, an iron overload disease caused by a deficiency in the iron-regulatory hormone hepcidin, is associated with lethal infections by siderophilic bacteria. To elucidate the ...mechanisms of this susceptibility, we infected wild-type and hepcidin-deficient mice with the siderophilic bacterium Vibrio vulnificus and found that hepcidin deficiency results in increased bacteremia and decreased survival of infected mice, which can be partially ameliorated by dietary iron depletion. Additionally, timely administration of hepcidin agonists to hepcidin-deficient mice induces hypoferremia that decreases bacterial loads and rescues these mice from death, regardless of initial iron levels. Studies of Vibrio vulnificus growth ex vivo show that high iron sera from hepcidin-deficient mice support extraordinarily rapid bacterial growth and that this is inhibited in hypoferremic sera. Our findings demonstrate that hepcidin-mediated hypoferremia is a host defense mechanism against siderophilic pathogens and suggest that hepcidin agonists may improve infection outcomes in patients with hereditary hemochromatosis or thalassemia.
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•During V. vulnificus infection, hepcidin is induced within hours, causing hypoferremia•Iron overload and hepcidin deficiency predispose mice to V. vulnificus infection•Hepcidin-induced hypoferremia restricts bacterial growth, even during iron overload•Treatment with hepcidin agonists averted mortality from V. vulnificus infection
The hepatic hormone hepcidin is a key regulator of iron homeostasis. Arezes et al. demonstrate that hepcidin is critical for host defense against Vibrio vulnificus, a deadly bacterial pathogen. Treatment with hepcidin agonist averted mortality in infected mice, highlighting the potential of hepcidin therapy in siderophilic infections.
This study probes the execution of internal quality assurance vis-à-vis learning outcome assessments in Japanese and Taiwanese universities. To this end, it applies Elken and Stensaker's theoretical ...framework of 'quality work' to ascertain the following: (1) how universities build internal quality assurance; (2) what learning outcome assessments are embedded in internal quality assurance mechanisms; (3) how universities perceive internal quality assurance in relation to learning outcome assessments. Both nations offer shared perspectives on the correlations between internal quality assurance and learning outcome assessments: (i) tasks are simultaneously performed; (ii) internal quality assurance is the purpose and learning outcome assessment is a means to achieve it; (iii) the two tasks are decoupled. However, only Japan evinces the internal quality assurance as supply (assessment) and demand (outcomes). The finding initiates discourse on the purpose of internal quality assurance and cautions against their construction solely in response to external requirements.
Erythropoietin (EPO) has been reported as a novel determinant of fibroblast growth factor 23 (FGF23) production; however, it is unknown whether FGF23 is stimulated by chronic exposure to EPO or by ...EPO administration in nonpolycystic chronic kidney disease (CKD) models.
We analyzed the effects of chronic EPO on FGF23 in murine models with chronically high EPO levels and normal kidney function. We studied the effects of exogenous EPO on FGF23 in wild-type mice, with and without CKD, injected with EPO. Also, in four independent human CKD cohorts, we evaluated associations between FGF23 and serum EPO levels or exogenous EPO dose.
Mice with high endogenous EPO have elevated circulating total FGF23, increased disproportionately to intact FGF23, suggesting coupling of increased FGF23 production with increased proteolytic cleavage. Similarly, in wild-type mice with and without CKD, a single exogenous EPO dose acutely increases circulating total FGF23 out of proportion to intact FGF23. In these murine models, the bone marrow is shown to be a novel source of EPO-stimulated FGF23 production. In humans, serum EPO levels and recombinant human EPO dose are positively and independently associated with total FGF23 levels across the spectrum of CKD and after kidney transplantation. In our largest cohort of 680 renal transplant recipients, serum EPO levels are associated with total FGF23, but not intact FGF23, consistent with the effects of EPO on FGF23 production and metabolism observed in our murine models.
EPO affects FGF23 production and metabolism, which may have important implications for CKD patients.
The impact of COVID-19 on higher education and quality assurance (QA) has already elicited global attention and discussion. QA agencies and networks quickly learned to adapt in order to carry out ...assessments, accreditations, recognitions, and reviews in a full virtual mode. These practices include using shared folders for virtual desk review, video conferencing platforms for interviews, and virtual site visits. In order to respond to the 2020 pandemic, The International Network for Quality Assurance Agencies in Higher Education (INQAAHE) swiftly adopted a virtual mode of the GGP review exercise for the GGP alignment applicants. The Higher Education Evaluation and Accreditation Council of Taiwan (HEEACT) was the first case that underwent a thorough virtual review process of GGP alignment during the 2020 pandemic. Therefore, this study aims to outline the impact of the pandemic in Taiwan higher education as well as provide the meta-analysis of the virtual review process of the INQAAHE GGP alignment by using HEEACT as a case study.
In chronic kidney disease, ferric citrate has been shown to be an effective phosphate binder and source of enteral iron; however, the effects of ferric citrate on the kidney have been less ...well-studied. Here, in Col4α3 knockout mice-a murine model of progressive chronic kidney disease, we evaluated the effects of five weeks of 1% ferric citrate dietary supplementation. As expected, ferric citrate lowered serum phosphate concentrations and increased serum iron levels in the Col4α3 knockout mice. Consistent with decreased enteral phosphate absorption and possibly improved iron status, ferric citrate greatly reduced circulating fibroblast growth factor 23 levels. Interestingly, ferric citrate also lessened systemic inflammation, improved kidney function, reduced albuminuria, and decreased kidney inflammation and fibrosis, suggesting renoprotective effects of ferric citrate in the setting of chronic kidney disease. The factors mediating possible ferric citrate renoprotection, the mechanisms by which they may act, and whether ferric citrate affects chronic kidney disease progression in humans deserves further study.
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