Investigating antibody-catalyzed ozone generation by human neutrophils

Abstract

Recent studies have suggested that antibodies can catalyze the generation of previously unknown oxidants including dihydrogen trioxide (H 2O3) and ozone (O3) from singlet oxygen ( 1 O 2 * ) and water. Given that neutrophils have the potential both to produce 1 O 2 * and to bind antibodies, we considered that these cells could be a biological source of O 3. We report here further analytical evidence that antibody-coated neutrophils, after activation, produce an oxidant with the chemical signature of O 3. This process is independent of surface antibody concentration down to 50% of the resting concentration, suggesting that surface IgG is highly efficient at intercepting the neutrophil-generated 1 O 2 * . Vinylbenzoic acid, an orthogonal probe for ozone detection, is oxidized by activated neutrophils to 4-carboxybenzaldehyde in a manner analogous to that obtained for its oxidation by ozone in solution. This discovery of the production of such a powerful oxidant in a biological context raises questions about not only the capacity of O 3 to kill invading microorganisms but also its role in amplification of the inflammatory response by signaling and gene activation. N eutrophils (PMNs) are the most abundant leukocytes in the bloodstream. Their function is the killing of bacteria and fungi, in part by the triggering of an oxidative burst that is composed of a set of enzymatic and chemical reactions ultimately leading to the formation of hypohalous acid, 1 O 2 * , and hydroxyl radical (HO • ) (1, 2). The first step in this cascade, the reduction of dioxygen, is initiated by the enzyme NAD(P)H oxidase. This oxidase is a complex enzyme composed of five components: gp91 phox (with phox being phagocyte oxidase), a heavily glycosylated 56-kDa protein that contains the electroncarrying components of the oxidase; p67 phox , p47 phox , and p22 phox , which are proteins named according to their approximate molecular weights; and rac2, a low molecular weight GTPase. In the resting cell, p47 phox and p67 phox form a complex in the cytosol (which also contains p40 phox , a protein whose effect on oxidase activity is unclear), whereas gp91 phox and p22 phox are in the membrane. When the PMN is activated by antibody-coated bacteria, p47 phox is phosphorylated on particular serines and moves to the membrane to assemble the active oxidase, carrying with it its cargo of p67 phox and the enigmatic p40 phox . Rac 2, also necessary for oxidase activity, picks up a GTP and moves into the oxidase assembly. The NAD(P)H oxidase then produces superoxide anion (O 2•Ϫ ) (Eq.

Ferrous Ions and Reactive Oxygen Species Increase Antigen-binding and Anti-inflammatory Activities of Immunoglobulin G

“…As a substrate for this reaction, immunoglobulins use singlet oxygen, generated and released during the respiratory burst from phagocytes at sites of inflammation. The role of the antibody-catalyzed water oxidation pathway in anti-bacterial defense, inflammation, and pathogenesis of atherosclerosis was demonstrated (22,36,37). It was shown by x-ray analysis that, during this reaction, a limited number of oxidative modifications of amino acid residues occur in the immunoglobulin molecules.…”

“…The generation of superoxide anion radicals by phagocytes, taking place during inflammation, synergizes with the immunoglobulin-catalyzed production of hydrogen peroxide and ozone (22,32,33,36,37). This oxidative burst also triggers the release of ferritin-(16) or transferrin-bound (17) ferrous ions that further amplify the reactive oxygen cascades.…”

Cyclooxygenase 2 Plays a Pivotal Role in the Resolution of Acute Lung Injury

“…ALI is characterized by neutrophil (polymorphonuclear leukocyte (PMN))-rich inflammation and flooding of alveolar spaces with fluid and protein secondary to a loss of barrier integrity (2). The robust inflammatory response to airway injury often leads to unintended tissue damage to surrounding lung via the release of oxidants, proteases, and other potentially toxic agents from activated leukocytes (3)(4)(5). No specific therapy is currently available to modulate this inflammatory response and protect the lung.…”

Study of Trace Elements in Bioarena System and in in Vivo Conditions

“…Figure 3b summarizes the reaction series supposedly taking into account the earlier and more recent determining observations. [19][20][21][22][23] This complex figure includes two fundamental, related biochemical pathways which can be studied in BioArena system.…”

“…[19,20] 1 O 2 can oxidize water molecules and -among others-ozone can be formed which is an important component of the adaptive immune system ( Figure 3B). [21][22][23] According to preliminary experiments and observations trace elements as carriers transport HCHO molecules in a dose-dependent manner to different points of a given biological unit.…”