Suppression of tomato wilt by cell-free supernatants of Acinetobacter baumannii isolates from wild cacao from the Colombian Amazon.

Tomato vascular wilt caused by Fusarium oxysporum f. sp. lycopersici (Fol) is one of the most limiting diseases of this crop. The use of fungicides and varieties resistant to the pathogen has not provided adequate control of the disease. In this study, siderophore-producing bacteria isolated from wild cocoa trees from the Colombian Amazon were characterized to identify prominent strategies for plant protection. The isolates were taxonomically classified into five different genera. Eight of the fourteen were identified as bacteria of the Acinetobacter baumannii complex. Isolates CBIO024, CBIO086, CBIO117, CBIO123, and CBIO159 belonging to this complex showed the highest efficiency in siderophore synthesis, producing these molecules in a range of 91-129 µmol/L deferoxamine mesylate equivalents. A reduction in disease severity of up to 45% was obtained when plants were pretreated with CBIO117 siderophore-rich cell-free supernatant (SodSid). Regarding the mechanism of action that caused antagonistic activity against Fol, it was found that plants infected only with Fol and plants pretreated with SodSid CBIO117 and infected with Fol showed higher levels of PR1 and ERF1 gene expression than control plants. In contrast, MYC2 gene expression was not induced by the SodSid CBIO117 application. However, it was upregulated in plants infected with Fol and plants pretreated with SodSid CBIO117 and infected with the pathogen. In addition to the disease suppression exerted by SodSid CBIO117, the results suggest that the mechanism underlying this effect is related to an induction of systemic defense through the salicylic acid, ethylene, and priming defense via the jasmonic acid pathway.

Deferoxamine Interference in Fibro-inflammation: Additional Action in Control of Obese Adipose Tissue Dysfunction.

INTRODUCTION: Several studies demonstrated that deferoxamine, an iron chelator, can improve inflammatory alterations in adipose tissue induced by obesity. Obesity alterations in adipose tissue are also associated with tissue remodeling, and deferoxamine has anti-fibrosis action previously described in sites like the skin and liver. METHODS: In this work, we analyzed deferoxamine effects on adipose tissue fibro-inflammation during obesity induced by diet in mice. in vitro approaches with fibroblasts and macrophages were also carried out to elucidate deferoxamine activity. RESULTS: Our results demonstrated that in addition to exerting anti-inflammatory effects, reducing the cytokine production in adipose tissue of obese mice and by human monocyte differentiated in macrophage in vitro, deferoxamine can alter metalloproteinases expression and extracellular matrix production in vivo and in vitro. CONCLUSION: Deferoxamine could be an alternative to control fibro-inflammation in obese adipose tissue, contributing to the metabolic improvements previously described.

Ryanodine Receptor Mediated Calcium Release Contributes to Ferroptosis Induced in Primary Hippocampal Neurons by GPX4 Inhibition.

Ferroptosis, a newly described form of regulated cell death, is characterized by the iron-dependent accumulation of lipid peroxides, glutathione depletion, mitochondrial alterations, and enhanced lipoxygenase activity. Inhibition of glutathione peroxidase 4 (GPX4), a key intracellular antioxidant regulator, promotes ferroptosis in different cell types. Scant information is available on GPX4-induced ferroptosis in hippocampal neurons. Moreover, the role of calcium (Ca2+) signaling in ferroptosis remains elusive. Here, we report that RSL3, a selective inhibitor of GPX4, caused dendritic damage, lipid peroxidation, and induced cell death in rat primary hippocampal neurons. Previous incubation with the ferroptosis inhibitors deferoxamine or ferrostatin-1 reduced these effects. Likewise, preincubation with micromolar concentrations of ryanodine, which prevent Ca2+ release mediated by Ryanodine Receptor (RyR) channels, partially protected against RSL3-induced cell death. Incubation with RSL3 for 24 h suppressed the cytoplasmic Ca2+ concentration increase induced by the RyR agonist caffeine or by the SERCA inhibitor thapsigargin and reduced hippocampal RyR2 protein content. The present results add to the current understanding of ferroptosis-induced neuronal cell death in the hippocampus and provide new information both on the role of RyR-mediated Ca2+ signals on this process and on the effects of GPX4 inhibition on endoplasmic reticulum calcium content.

New Insights into Oxidative Damage and Iron Associated Impairment in Traumatic Brain Injury.

Traumatic Brain Injury is considered one of the most prevalent causes of death around the world; more than seventy millions of individuals sustain the condition per year. The consequences of traumatic brain injury on brain tissue are complex and multifactorial, hence, the current palliative treatments are limited to improve patients' quality of life. The subsequent hemorrhage caused by trauma and the ongoing oxidative process generated by biochemical disturbances in the in the brain tissue may increase iron levels and reactive oxygen species. The relationship between oxidative damage and the traumatic brain injury is well known, for that reason, diminishing factors that potentiate the production of reactive oxygen species have a promissory therapeutic use. Iron chelators are molecules capable of scavenging the oxidative damage from the brain tissue and are currently in use for ironoverload- derived diseases. Here, we show an updated overview of the underlying mechanisms of the oxidative damage after traumatic brain injury. Later, we introduced the potential use of iron chelators as neuroprotective compounds for traumatic brain injury, highlighting the action mechanisms of iron chelators and their current clinical applications.

New Perspectives in Iron Chelation Therapy for the Treatment of Neurodegenerative Diseases.

Iron chelation has been introduced as a new therapeutic concept for the treatment of neurodegenerative diseases with features of iron overload. At difference with iron chelators used in systemic diseases, effective chelators for the treatment of neurodegenerative diseases must cross the blood⁻brain barrier. Given the promissory but still inconclusive results obtained in clinical trials of iron chelation therapy, it is reasonable to postulate that new compounds with properties that extend beyond chelation should significantly improve these results. Desirable properties of a new generation of chelators include mitochondrial destination, the center of iron-reactive oxygen species interaction, and the ability to quench free radicals produced by the Fenton reaction. In addition, these chelators should have moderate iron binding affinity, sufficient to chelate excessive increments of the labile iron pool, estimated in the micromolar range, but not high enough to disrupt physiological iron homeostasis. Moreover, candidate chelators should have selectivity for the targeted neuronal type, to lessen unwanted secondary effects during long-term treatment. Here, on the basis of a number of clinical trials, we discuss critically the current situation of iron chelation therapy for the treatment of neurodegenerative diseases with an iron accumulation component. The list includes Parkinson's disease, Friedreich's ataxia, pantothenate kinase-associated neurodegeneration, Huntington disease and Alzheimer's disease. We also review the upsurge of new multifunctional iron chelators that in the future may replace the conventional types as therapeutic agents for the treatment of neurodegenerative diseases.

An optimized low-cost protocol for standardized production of iron-free apoferritin nanocages with high protein recovery and suitable conformation for nanotechnological applications.

Ferritin is a globular protein that consists of 24 subunits forming a hollow nanocage structure that naturally stores iron oxyhydroxides. Elimination of iron atoms to obtain the empty protein called apoferritin is the first step to use this organic shell as a nanoreactor for different nanotechnological applications. Different protocols have been reported for apoferritin formation, but some are time consuming, others are difficult to reproduce and protein recovery yields are seldom reported. Here we tested several protocols and performed a complete material characterization of the apoferritin products using size exclusion chromatography, UV-vis spectroscopy, inductively coupled plasma optical emission spectrometry and dynamic light scattering. Our best method removes more than 99% of the iron from loaded holoferritin, recovering 70-80% of the original protein as monomeric apoferritin nanocages. Our work shows that pH conditions of the reduction step and the presence and nature of chelating agents affect the efficiency of iron removal. Furthermore, process conditions also seem to have an influence on the monomer:aggregate proportion present in the product. We also demonstrate that iron contents markedly increase ferritin absorbance at 280nm. The influence of iron contents on absorbance at 280nm precludes using this simple spectrophotometric measure for protein determination in ferritin­iron complexes. Apoferritin produced following our protocol only requires readily-available, cheap and biocompatible reagents, which makes this process standardizable, scalable and applicable to be used for in vivo applications of ferritin derivatives as well as nanotechnological and biotechnological uses.

Modulatory effect of iron chelators on adenosine deaminase activity and gene expression in Trichomonas vaginalis

Trichomonas vaginalis is a flagellate protozoan that parasitises the urogenital human tract and causes trichomoniasis. During the infection, the acquisition of nutrients, such as iron and purine and pyrimidine nucleosides, is essential for the survival of the parasite. The enzymes for purinergic signalling, including adenosine deaminase (ADA), which degrades adenosine to inosine, have been characterised in T. vaginalis. In the evaluation of the ADA profile in different T. vaginalisisolates treated with different iron sources or with limited iron availability, a decrease in activity and an increase in ADA gene expression after iron limitation by 2,2-bipyridyl and ferrozine chelators were observed. This supported the hypothesis that iron can modulate the activity of the enzymes involved in purinergic signalling. Under bovine serum limitation conditions, no significant differences were observed. The results obtained in this study allow for the assessment of important aspects of ADA and contribute to a better understanding of the purinergic system in T. vaginalis and the role of iron in establishing infection and parasite survival.

Protective action of deferiprone and deferoxamine in erythrocytes isolated from patients with B-thalassemias / Ação protetora de deferiprona e desferoxamina nos eritrócitos isolados de pacientes com B-talassemias

One of the most deleterious consequences of iron overload in thalassemia is the presence of non-transferrin bound iron (NTBI), a free radical that acts as a catalyst for free oxygen radicals, in particular for hydroxyl free radicals (OH.). These radicals oxidize both membrane lipids and proteins causing irreversible damage to biologically important molecules and cellular structures. Treatment with iron chelators has been important to improve survival of these individuals. The aim of this work was the study on the effects of deferoxamine (DFO) and deferiprone (DFP) on erythrocytes under the pro-oxidative action of TBHP isolated from normal individuals and patients with β-thalassemia. The in vitro action of deferoxamine and deferiprone on the oxidative metabolism of erythrocytes from β-thalassemic patients treated at the Centro de Hematologia e Hemoterapia do Paraná (HEMEPAR), Brazil, under the pro-oxidative action of TBHP was studied. Methemoglobin concentrations, reduced glutathione (GSH), hemolysis indexes and the enzyme activities of G6-PD and GR were determined. The oxidation indexes were higher in erythrocytes of β-thalassemic individuals than those from normal individuals. Treatment of the normal and β-thalassemic erythrocytes with DFO and/or DFP protected against the formation of GSH promoted by TBHP.

Uma das maiores consequências da sobrecarga do ferro na β-talassemia é a presença de ferro não ligado à transferrina (NTBI), um radical livre que age como um catalisador do radical livre do oxigênio, particularmente radical hidroxil (OH.). Estes radicais oxidam os lipídeos e as proteínas da membrana causando danos irreversíveis às moléculas biologicamente importantes e às estruturas celulares. O tratamento com quelantes do ferro é importante para a melhoria da sobrevivência destes indivíduos. O objetivo deste trabalho foi o estudo sobre o efeito da desferoxamina (DFO) e da deferiprona (DFP) em eritrócitos isolados de indivíduos normais e de pacientes com β-talassemias, sob a ação pró-oxidativa de TBHP. Neste trabalho foi estudada a ação in vitro da desferoxamina e o deferiprona no metabolismo oxidativo dos eritrócitos de pacientes β-talassêmicos atendidos no Centro de Hematologia e Hemoterapia do Paraná (Hemepar), Brasil, sob a ação pró-oxidativa de TBHP. Concentrações de metahemoglobina glutationa reduzida, índices de hemólises, atividades das enzimas G6PD e GR foram determinadas. Os índices de oxidação analisados foram maiores nos eritrócitos de indivíduos β-talassêmicos do que nos normais. Tratamentos dos eritrócitos normais e β-talassêmicos com DFO e/ou DFP protegem contra a oxidação de GSH promovida por TBHP.