title: Ferrous iron is found in mesenteric lymph bound to TIMP-2 following hemorrhage/resuscitation.
abstract: Extracellular iron has been implicated in the pathogenesis of post-injury organ failure. However, the source(s) and biochemical species of this iron have not been identified. Based upon evidence that distant organ injury results from an increase in intestinal permeability, we looked for ferrous iron in mesenteric lymph in anesthetized rats undergoing hemorrhage and fluid resuscitation (H/R). Ferrous iron increased in lymph from 4.7 nmol/mg of protein prior to hemorrhage to 86.6 nmol/mg during resuscitation. Utilizing immuno-spin trapping in protein fractions that were rich in iron, we tentatively indentified protein carrier(s) of ferrous iron by MALDI-TOF MS. One of the identified proteins was the metalloproteinase (MMP) inhibitor, TIMP-2. Antibody to TIMP-2 immunoprecipitated 74% of the ferrozine detectable iron in its protein fraction. TIMP-2 binds iron in vitro at pH 6.3, which is typical of conditions in the mesentery during hemorrhage, but it retains the ability to inhibit the metalloproteases MMP-2 and MMP-9. In summary, there is a large increase in extracellular ferrous iron in the gut in H/R demonstrating dysregulation of iron homeostasis. We have identified, for the first time, the binding of extracellular iron to TIMP-2.
authors.affiliation: Closed Head Brain Injury Branch, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research, 503 Robert Grant Ave., Silver Spring, MD 20910-7500, USA. jim.atkins@us.army.mil
authors.forename: James L
authors.initials: JL
authors.lastname: Atkins
authors.forename: Nikolai V
authors.initials: NV
authors.lastname: Gorbunov
authors.forename: Valerie
authors.initials: V
authors.lastname: Trabosh
authors.forename: Rachel
authors.initials: R
authors.lastname: Van Duyne
authors.forename: Fatah
authors.initials: F
authors.lastname: Kashanchi
authors.forename: Andrei M
authors.initials: AM
authors.lastname: Komarov
mesh_terms: D000818:Animals; D002850:Chromatography, Gel; D004578:Electron Spin Resonance Spectroscopy; D006470:Hemorrhage / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D047468:Immunoprecipitation; D007501:Iron / Q000378:metabolism*; D008297:Male; D061965:Matrix Metalloproteinase Inhibitors; D051381:Rats; D017207:Rats, Sprague-Dawley; D012151:Resuscitation; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D061965:Matrix Metalloproteinase Inhibitors; D019716:Tissue Inhibitor of Metalloproteinase-2; D007501:Iron