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PlasmaThe Non-cellular Components of Blood
Published in Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal, Principles of Physiology for the Anaesthetist, 2020
Peter Kam, Ian Power, Michael J. Cousins, Philip J. Siddal
Transferrin is the plasma protein that transports iron. Apotransferrin, its precursor, is produced in the liver. One molecule of transferrin will bind two ferric ions and is normally approximately one-third saturated with iron. Haemopexin is a β-globulin that binds to haem and releases it to the reticuloendothelial system.
The Acute Phase Response: An Overview
Published in Andrzej Mackiewicz, Irving Kushner, Heinz Baumann, Acute Phase Proteins, 2020
Irving Kushner, Andrzej Mackiewicz
The APP which belong to this group play an important role in protecting host tissues from toxic oxygen metabolites released from phagocytic cells during inflammatory states,30 an important function since reactive oxygen metabolites, when not controlled, can cause injury of host cells. Ceruloplasmin is involved in copper transport and antioxidant defense,31 the latter by inhibiting copper ion-stimulated formation of reactive oxidants and the scavengers H2O2 and superoxide. Hemopexin binds heme released from damaged heme-containing proteins.32Haptoglobin (Hp) binds hemoglobin released during hemolysis. Recently, it has also been shown to stimulate angiogenesis.33 Clearance of free hemoglobin34 is very important since hemoglobin can accelerate lipid peroxidation, leading to production of toxic molecules.35
Changes in Gene Expression During Aging of Mammals
Published in Alvaro Macieira-Coelho, Molecular Basis of Aging, 2017
Infection, wounding, or chronic diseases cause inflammation in an animal resulting in significant changes in the levels of plasma proteins. This response takes place primarily in the liver and is called “acute phase reaction”, in which hepatic genes are stimulated leading to production of proteins that enter the blood. Several plasma proteins, such as T-kininogen, fibrinogen, α-1-acid glycoprotein, C-reactive protein, hemopexin, ceruloplasmin, and haptoglobin increase in level. These are called “positive acute phase reactants”. Certain proteins such as albumin, transthyretin, 2-HS-glycoprotein, transferrin, and apolipoprotein A-1 decrease in level. They are “negative acute phase reactants”.
Halogen gas exposure: toxic effects on the parturient
Published in Toxicology Mechanisms and Methods, 2021
Dylan R. Addis, James A. Lambert, David A. Ford, Tamas Jilling, Sadis Matalon
In mice post-exposure to Br2, elevated levels of heme were found in lung tissue, bronchoalveolar lavage (BAL) fluid, and plasma. Increased measured heme levels correlated with lung injury, inflammation, and oxidative stress. Facilitation of heme degradation by hemopexin administered post-exposure improved survival of the mice and reduced lung injury and inflammation (Lam et al. 2016). Additionally, in mice exposed to Br2 a biphasic pattern of morbidity and mortality is observed with a high immediate mortality followed by a 4–5 day plateau leading into a subsequent second spike in mortality (Aggarwal et al. 2016; Lam et al. 2016). This second, chronic phase of injury is characterized by peribronchial fibrosis and emphysema-like enlargement of alveoli (Aggarwal et al. 2018). The developing lung appears to be especially sensitive to the toxic effects of bromine. Exposure of neonatal mice to bromine resulted in impaired alveolar development, inflammation, and altered gene expression indicative of severe derangements in lung development (Jilling et al. 2018).
Serum proteome assessment in nonalcoholic fatty liver disease in children: a preliminary study
Published in Expert Review of Proteomics, 2020
Paweł Małecki, Joanna Tracz, Magdalena Łuczak, Magdalena Figlerowicz, Katarzyna Mazur-Melewska, Wojciech Służewski, Anna Mania
In the serum proteome analysis of patients with NAFLD, Miller et al. also found a significantly elevated concentration of afamine compared to the control group. Convergent results were found for hemopexin. It is an acute-phase protein responsible for binding and detoxification of free heme, the synthesis of which is induced during inflammatory states to minimize tissue injury and facilitate tissue repair. Moreover, as in our research, the concentration of DBP was significantly lower in patients and NAFLD [43]. The pathomechanism of this phenomenon is not known. The primary biologic function of DBP is regulation of the circulating free and total levels of vitamin D metabolites. Furthermore, DBP plays a role in fatty acid-binding, actin scavenging, neutrophil recruitment, and formation of the DBP-macrophage activating factor during the inflammatory process. The protein is produced mainly in the liver, and its level depends on various factors – hormones and inflammatory cytokines [44].
Iron homeostasis in host and gut bacteria – a complex interrelationship
Published in Gut Microbes, 2021
Yohannes Seyoum, Kaleab Baye, Christèle Humblot
Iron is exported from the cell by a major protein, ferroportin, that is present on the basolateral membrane.25,33 Ferroportin is mainly expressed by cells and tissues associated with iron transfer to plasm, i.e., duodenal enterocytes, liver Kupffer cells, splenic red pulp macrophages, periportal hepatocytes, and the placental syncytiotrophoblast.34 Following export of ferrous iron across the basal membrane by ferroportin, it is then oxidized by a multi-copper oxidase protein called hephaestin before being bound by plasma transferrin.35 Other proteins such as breast cancer resistance protein (Bcrp)/ATP-binding cassette subfamily G member 2 (Abcg2) and feline leukemia virus C receptor (FLVCR) have been reported to be responsible for the export of heme iron out of the cell, but although, but some heme iron traverses the cells intact, the underlying mechanism is still not known.36 The exported free heme is complexed with hemopexin into a heme-hemopexin complex, which can be directly absorbed by cluster of differentiation (CD91) receptors on the liver and macrophage.37 Iron released into the circulatory system binds to transferrin in the blood, which then binds to transferrin receptor-1 (TfR1) on the cell surface and delivers its cargo to the cytosol via endocytosis.22 In these more acidic conditions, iron dissociates from transferrin and is then reduced by ferrireductases to cross the endosomal membrane via DMT1. Another transferrin receptor, the type 2 transferrin receptor (TfR-2), largely restricted to liver and erythroid precursors, also interacts with holo-transferrin but does not substantially contribute to iron uptake, rather as a sensor of systemic iron status.38,39