Imaging of myeloperoxidase in mice by using novel amplifiable paramagnetic substrates.

PURPOSE To evaluate whether contrast agents for molecular magnetic resonance (MR) imaging can demonstrate the in vivo activity of myeloperoxidase, an enzyme that is secreted by stimulated polymorphonuclear leukocytes, monocytes, and macrophages during inflammation. MATERIALS AND METHODS Animal experiments were approved by the animal care committee. Protocols for the procurement and use of human blood were approved by the institutional review board. Informed consent was obtained from each donor, and HIPAA guidelines were followed for humans. Two paramagnetic myeloperoxidase substrates--that is, gadolinium-5-hydroxytryptamide-tetraazacyclododecane tetraacetic acid (Gd-5-HT-DOTA) and Gd-bis-5-HT-diethylenetriaminepentaacetic acid (Gd-bis-5-HT-DTPA)--were synthesized. Indium 111-labeled bis-5-HT-DTPA was used to determine biodistribution and target localization. A total of 22 mice were used in three models. In the first model, human myeloperoxidase was embedded in a basement membrane matrix gel and was injected intramuscularly. In the second model, lipopolysaccharide (LPS) from Escherichia coli was embedded in a basement membrane matrix gel and was injected intramuscularly to induce endogenous myeloperoxidase secretion. In the third model, LPS was injected intramuscularly to induce myositis. Statistical significance was calculated for contrast-to-noise ratio (CNR) curves by using the Kolmogorov-Smirnov test. RESULTS After the administration of Gd-bis-5-HT-DTPA, strong MR signal enhancement (up to 2.5-fold increase in CNR, P < .001) was observed in vivo for implants that contained human myeloperoxidase. In the LPS-induced myositis model, a smaller visible difference was seen (1.3-fold increase in CNR, P < .001), which was consistent with the fact that endogenous mouse myeloperoxidase is only about 10%-20% as active as human myeloperoxidase. Prolonged contrast material enhancement was observed in the myeloperoxidase-containing areas that were injected with Gd-5-HT-DOTA or Gd-bis-5-HT-DTPA but was not observed in areas that were injected with Gd-DTPA or Gd-dopamine-DOTA (P < .05). Single photon emission computed tomography combined with computed tomography was used to confirm the increased retention of contrast agents at sites that contained human myeloperoxidase, and the results of biodistribution studies demonstrated a more than fourfold increase radiotracer accumulation at these sites. CONCLUSION Human and mouse myeloperoxidase activity in myeloperoxidase implants and inflamed tissues can be visualized and reported in vivo by using myeloperoxidase-sensitive "smart" molecular imaging probes.

[1]  Stanley L Hazen,et al.  ATVB in Focus Redox Mechanisms in Blood Vessels , 2005 .

[2]  R. Weissleder,et al.  DTPA-bisamide-based MR sensor agents for peroxidase imaging. , 2005, Organic letters.

[3]  R. Weissleder,et al.  Human myeloperoxidase: A potential target for molecular MR imaging in atherosclerosis , 2004, Magnetic resonance in medicine.

[4]  A. Chait,et al.  The myeloperoxidase product hypochlorous acid oxidizes HDL in the human artery wall and impairs ABCA1-dependent cholesterol transport. , 2004, Proceedings of the National Academy of Sciences of the United States of America.

[5]  D. Epps,et al.  Altered function of synovial fluid granulocytes in patients with acute inflammatory arthritis , 1986, Inflammation.

[6]  Chunxiang Zhang,et al.  Interaction of myeloperoxidase with vascular NAD(P)H oxidase-derived reactive oxygen species in vasculature: implications for vascular diseases. , 2003, American journal of physiology. Heart and circulatory physiology.

[7]  E. Topol,et al.  Prognostic value of myeloperoxidase in patients with chest pain. , 2003, The New England journal of medicine.

[8]  E. Boerwinkle,et al.  From vulnerable plaque to vulnerable patient: a call for new definitions and risk assessment strategies: Part I. , 2003, Circulation.

[9]  Antonio Colombo,et al.  From vulnerable plaque to vulnerable patient: a call for new definitions and risk assessment strategies: Part II. , 2003, Circulation.

[10]  C. Heeschen,et al.  Myeloperoxidase Serum Levels Predict Risk in Patients With Acute Coronary Syndromes , 2003, Circulation.

[11]  P. Libby Inflammation in atherosclerosis , 2002, Nature.

[12]  R. Weissleder,et al.  Oligomerization of paramagnetic substrates result in signal amplification and can be used for MR imaging of molecular targets. , 2002 .

[13]  W. Parks,et al.  Hypochlorous Acid Oxygenates the Cysteine Switch Domain of Pro-matrilysin (MMP-7) , 2001, The Journal of Biological Chemistry.

[14]  J. Crowley,et al.  Increased atherosclerosis in myeloperoxidase-deficient mice. , 2001, The Journal of clinical investigation.

[15]  D. Kutter,et al.  Consequences of Total and Subtotal Myeloperoxidase Deficiency: Risk or Benefit ? , 2000, Acta Haematologica.

[16]  M. Tien Myeloperoxidase-catalyzed oxidation of tyrosine. , 1999, Archives of biochemistry and biophysics.

[17]  E. Masliah,et al.  Myeloperoxidase Polymorphism Is Associated with Gender Specific Risk for Alzheimer's Disease , 1999, Experimental Neurology.

[18]  S J London,et al.  Myeloperoxidase genetic polymorphism and lung cancer risk. , 1997, Cancer research.

[19]  D. Douer,et al.  An allelic association implicates myeloperoxidase in the etiology of acute promyelocytic leukemia. , 1997, Blood.

[20]  B. Becher,et al.  Immunohistochemical and genetic evidence of myeloperoxidase involvement in multiple sclerosis , 1997, Journal of Neuroimmunology.

[21]  M. Desmadril,et al.  Horseradish peroxidase oxidation of tyrosine-containing peptides and their subsequent polymerization: a kinetic study. , 1997, Biochemistry.

[22]  J. Heinecke Pathways for oxidation of low density lipoprotein by myeloperoxidase: tyrosyl radical, reactive aldehydes, hypochlorous acid and molecular chlorine , 1997, BioFactors.

[23]  A. Daugherty,et al.  Myeloperoxidase, a catalyst for lipoprotein oxidation, is expressed in human atherosclerotic lesions. , 1994, The Journal of clinical investigation.

[24]  G. Francis,et al.  Tyrosyl radical generated by myeloperoxidase catalyzes the oxidative cross-linking of proteins. , 1993, The Journal of clinical investigation.

[25]  P. Schuff-Werner,et al.  Oxidation of the indole nucleus of 5-hydroxytryptamine and formation of dimers in the presence of peroxidase and H2O2. , 1990, Journal of neural transmission. Supplementum.

[26]  A. Napolitano,et al.  A profile of the oxidation chemistry of 5-hydroxyindole under biomimetic conditions , 1988 .

[27]  T. Kensler,et al.  Oxidant-dependent metabolic activation of polycyclic aromatic hydrocarbons by phorbol ester-stimulated human polymorphonuclear leukocytes: possible link between inflammation and cancer. , 1985, Proceedings of the National Academy of Sciences of the United States of America.

[28]  H. Rosen,et al.  [52] Antimicrobial activity of myeloperoxidase , 1984 .

[29]  R. Clark,et al.  Myeloperoxidase-catalyzed inactivation of alpha 1-protease inhibitor by human neutrophils. , 1981, The Journal of biological chemistry.

[30]  S. Klebanoff Oxygen metabolism and the toxic properties of phagocytes. , 1980, Annals of internal medicine.

[31]  K. Pryzwansky,et al.  Immunocytochemical identification of azurophilic and specific granule markers in the giant granules of Chediak-Higashi neutrophils. , 1978, The New England journal of medicine.

[32]  P. Rausch,et al.  Granule enzymes of polymorphonuclear neutrophils: A phylogenetic comparison. , 1975, Blood.