Effects of marginal iron overload on iron homeostasis and immune function in alveolar macrophages isolated from pregnant and normal rats.
; ; et al
in Biometals (2009), 22(2), 211-23
The effects of changes in macrophage iron status, induced by single or multiple iron injections, iron depletion or pregnancy, on both immune function and mRNA expression of genes involved in iron influx ... [more ▼]
The effects of changes in macrophage iron status, induced by single or multiple iron injections, iron depletion or pregnancy, on both immune function and mRNA expression of genes involved in iron influx and egress have been evaluated. Macrophages isolated from iron deficient rats, or pregnant rats at day 21 of gestation, either supplemented with a single dose of iron dextran, 10 mg, at the commencement of pregnancy, or not, showed significant increases of macrophage ferroportin mRNA expression, which was paralleled by significant decreases in hepatic Hamp mRNA expression. IRP activity in macrophages was not significantly altered by iron status or the inducement of pregnancy +/- a single iron supplement. Macrophage immune function was significantly altered by iron supplementation and pregnancy. Iron supplementation, alone or combined with pregnancy, increased the activities of both NADPH oxidase and nuclear factor kappa B (NFkappaB). In contrast, the imposition of pregnancy reduced the ability of these parameters to respond to an inflammatory stimuli. Increasing iron status, if only marginally, will reduce the ability of macrophages to mount a sustained response to inflammation as well as altering iron homeostatic mechanisms. [less ▲]Detailed reference viewed: 5 (0 ULg)
Unusual traits of the pyoverdin-mediated iron acquisition system in Pseudomonas putida strain BTP1.
Ongena, MARC ; ; et al
in Biometals (2002), 15(1), 1-13
Fluorescent Pseudomonas species are characterized by the production of pyoverdin-type siderophores for Fe3+ acquisition in iron-limited environments. Since it produces a structurally specific pyoverdin ... [more ▼]
Fluorescent Pseudomonas species are characterized by the production of pyoverdin-type siderophores for Fe3+ acquisition in iron-limited environments. Since it produces a structurally specific pyoverdin, Pseudomonas putida strain BTP1 could represent a valuable tool in an attempt to correlate the structural features of these compounds with some specificity in their two main properties i.e. affinity for iron and recognition rate by other Pseudomonas strains. An uncommonly high affinity for iron of the pyoverdin synthetized by P. putida BTP1 was observed by comparing both the apparent stability constant and the decomplexation kinetic of its ferric complex with those of ferripyoverdins from other strains. On another hand, results from growth stimulation experiments and labeled ferripyoverdin uptake assays highlighted the very low recognition rate of BTP1 isopyoverdins by membrane receptors of foreign strains. By contrast, P. putida BTP1 was able to utilize a broad spectrum of structurally unrelated exogenous pyoverdins by means of multiple receptors that are likely constitutively expressed in its outer membrane. The unusual traits of its pyoverdin-mediated iron acquisition system should contribute to enlarge the ecological competence of Pseudomonas putida BTP1 in terms of colonization and persistence in the rhizosphere. [less ▲]Detailed reference viewed: 14 (0 ULg)
An Electron Spin Resonance (Esr) Study on the Mechanism of Ascorbyl Radical Production by Metal-Binding Proteins
Mouithys-Mickalad, Ange ; ; Dupont, Ginette et al
in Biometals (1998), 11(2), 81-8
The mechanism of ascorbate oxidation by metal-binding proteins (ceruloplasmin, albumin and transferrin) was investigated in vitro and in isolated plasma by the measurement of the ascorbyl free radicals ... [more ▼]
The mechanism of ascorbate oxidation by metal-binding proteins (ceruloplasmin, albumin and transferrin) was investigated in vitro and in isolated plasma by the measurement of the ascorbyl free radicals (AFR) by electron spin resonance (ESR). In plasma of 13 healthy volunteers, a spontaneous and variable production of AFR was detected, which was increased by a 10(-4) M ascorbate overloading; however, this increase was not correlated to the intensity of the spontaneous AFR signal. The addition of Cu2+ and ceruloplasmin to plasma increased the ESR signal, while the addition of transferrin decreased the signal intensity in a dose-dependent manner. In vitro, we demonstrated that ascorbate was oxidized by human serum albumin and by ceruloplasmin, and that this oxidase-like activity was lost by trypsin or heat treatment of these proteins. These two proteins positively interacted in the oxidation of ascorbate, since addition of crude albumin to a solution of ascorbate and ceruloplasmin increased the intensity of ESR signal in a dose-dependent manner. The treatment of albumin by a metal chelator (DDTC) abolished these positive interactions. The respective roles of copper and iron in ascorbate oxidation were studied and showed a dose-dependent effect of these ions on ascorbate oxidation. The role of iron was confirmed by the inhibiting effect of metal-free transferrin on iron-dependent ascorbate oxidation. Concerted actions between iron carrying albumin and copper carrying ceruloplasmin appear responsible for the production of AFR in vitro and in vivo. [less ▲]Detailed reference viewed: 19 (3 ULg)